Improved solder production process

ABSTRACT

A process for the production of a crude solder composition includes the provision of a first solder refining slag that includes tin and/or lead. The process further
         includes the steps of partially reducing the first solder refining slag, thereby forming a crude solder metal composition and a second solder refining slag, followed by separating the second solder refining slag from the crude solder metal composition,   and partially reducing the second solder refining slag, thereby forming a second lead-tin based metal composition and a second spent slag followed by separating the second spent slag from the second lead-tin based metal composition       

     A copper containing fresh feed is added to step (ii), preferably before reducing the second solder refining slag.

FIELD OF THE INVENTION

The present invention relates to the production of non-ferrous metals bypyrometallurgy, in particular the production of so-called solderproducts. More particularly, the invention relates to an improvedprocess for the coproduction of copper and solder streams from primaryand secondary feedstocks, as prime products for further upgrade to metalproducts of commercially desirable purities. Solder streams often belongto the family of metal compositions or alloys that contain significantamounts of tin (Sn), usually but not necessarily together with lead(Pb).

BACKGROUND OF THE INVENTION

The non-ferrous metals may be produced from fresh ores as the startingmaterials, also called primary sources, or from recyclable materials,also known as secondary feedstocks, or from a combination thereof.Recyclable materials may for instance be by-products, waste materialsand end-of-life materials. The recovery of non-ferrous metals fromsecondary feedstocks has become an activity of paramount importance overthe years. The recycling of non-ferrous metals after use has become akey contributor in the industry, because the demand for the metalscontinues to be strong and the availability of high quality fresh metalores is reducing. In particular for the production of copper, itsrecovery from secondary feedstocks has become of significant industrialimportance. In addition, the reducing availability of high quality freshmetal ores has also lead to a gain in importance of the recovery ofnon-ferrous metals from lower quality metal feedstock. The lower qualitymetal feedstocks for copper recovery may e.g. contain significantamounts of other non-ferrous metals. These other metals may bythemselves have significant potential commercial value, such as tinand/or lead, but these primary and secondary feedstocks may containother metals with a lower or even no economic value at all, such aszinc, bismuth, antimony, arsenic or nickel. Often these other metals areundesired in the prime non-ferrous metal products, or may only beallowable at very limited levels.

The materials available as feedstock for the production of copper thustypically contain a plurality of metals. Secondary feedstocks rich incopper are for instance bronze, principally an alloy of copper and tin,and brass, an alloy of mainly copper and zinc.

These different metals need to be separated from the copper in theproduction process. The feedstocks may in addition include smallproportions of a range of other elements including iron, bismuth,antimony, arsenic, aluminium, manganese, sulphur, phosphorus andsilicon, most of which having a limited acceptability in a prime metalproduct.

Secondary feedstocks containing copper may also be end-of-lifeelectronic and/or electrical parts. These feedstocks typically comprisein addition to copper, the solder components, mainly tin and lead, butusually also comprise further metals such as iron and aluminium, plusoccasionally minor amounts of precious metals, and also non-metallicparts, such as plastics, paint, rubber, glue, wood, paper, cardboard,etc. . . . . These feedstocks are typically not clean, and thus usuallyalso contain further impurities such as dirt, grease, waxes, soil and/orsand. Many metals in such raw materials are often also partiallyoxidized.

Because the feedstocks having lower purities and higher contaminantlevels, both primary and secondary feedstocks, are much more abundantlyavailable, there is a need for broadening the capabilities ofnon-ferrous metal production processes for increasing the allowance ofsuch low grade raw materials as part of the feedstocks for the recoveryor production of non-ferrous metals such as copper.

The non-ferrous metal production processes typically contain at leastone and usually a plurality of pyrometallurgical process steps. A verycommon first pyrometallurgical step for recovering copper from low gradesecondary materials is a smelting step. In a smelting furnace the metalsare molten, and organics and other combustible materials are burned off.In addition, various chemical reactions take place between various ofthe other components that are introduced into the smelter furnace.Metals having a relatively high affinity for oxygen convert to theiroxides and collect in the lower density supernatant slag phase. Morevolatile metals may escape the liquid into the gas phase and leave thefurnace with the exhaust gasses, together with any carbon oxides and/orSO₂ that may be formed. The metals having a lower affinity for oxygen,if present in oxidized state readily reduce to their elemental metalform and move to the heavier and underlying metal phase. If notoxidized, these metals remain as elemental metal and remain in thehigher density liquid metal phase in the bottom of the smelter furnace.In a copper production step, the smelting step may be operated such thatmost iron ends up in the slag, while copper, tin and lead end up in themetal product, a stream which is typically called “black copper”. Alsomost of the nickel, antimony, arsenic and bismuth typically end up aspart of the black copper product.

U.S. Pat. No. 3,682,623, which is a family member of AU 505 015 B2,describes a copper refining process starting with a melting step leadingto a black copper stream, followed by the further pyrometallurgicalstepwise refining of this black copper to an anode grade copper stream,suitable for being cast into anodes for electrolytic refining. Theby-product slags from the copper refining slags were accumulated andtransferred to a slag retreating furnace for recovery of the copper,lead and tin contained in those slags. In a first slag retreatment step,the accumulated copper refining slags were partially reduced, by theaddition of copper/iron scrap, copper/aluminium alloy and burnt lime,such that a metal stream could be separated off (Table XIV) whichrecovered about 90% of the copper and about 85% of the nickel in thefurnace. This tapped metal stream is in U.S. Pat. No. 3,682,623 labelled“black copper” and was recycled to the refining furnace, where it wasmixed with the pre-refined black copper coming from the melting furnaceand with radiators (Table VI). After tapping this black copper, anextracted slag remained in the furnace, which slag was in a subsequentstep further reduced by charging to the furnace an amount of 98% ironscrap. This second reduction step yielded a lead/tin metal (i.e. a kindof “crude solder”) which was tapped off for further processing, togetherwith a spent slag (Table XV), which was presumably discarded. The soldermetal product contained 3.00% wt of iron, 13.54% wt of copper and 1.57%wt of nickel, i.e. 18.11% wt in total. The spent slag contained 0.50% wteach of tin and lead, and 0.05% wt of copper. Because the total amountof slag is very high, these low concentrations represent economicallyhigh amounts.

The problem with the process of U.S. Pat. No. 3,682,623 is that, inorder to achieve in the end slag shown in Table XV the lowconcentrations of metals of concern in terms of ecology and economy, ahigh amount of contaminants must be accepted in the lead/tin metalobtained for further processing.

The purity of the products in U.S. Pat. No. 3,682,623 is not perfect.The metals other than tin and lead in the crude solder represent aburden for the further processing of these product streams to obtaincommercially valuable metal products. The crude solder in U.S. Pat. No.3,682,623 contains 3.00% wt of iron, 1.57% wt of nickel and 13.54% wt ofcopper, all of which representing a process burden because these metalscause a significant consumption of chemicals in the further refining ofthe solder, not only but in particular if the solder refining would beperformed as described in DE 102012005401 A1, i.e. by treatment withsilicon metal, which is a rather scarce and hence expensive reagent.

DE 102012005401 A1 describes a process for the production of copper fromsecondary feedstocks, starting with a step for melting the rawmaterials. The smelting step is described to yield a slag phasecontaining copper, tin, lead and nickel. The slag was transferred into arotary drum furnace for further processing. This further processingconsisted of a series of consecutive partial chemical reduction steps,using carbon as a reducing agent, for consecutive recovery of particularmetal products that are each time separated and removed from thefurnace. A first “preliminary” step (“Vorstufe”) performed on thesmelter slag recovered a copper product for processing in an anodefurnace. In order to obtain copper of sufficiently high quality, most ofthe tin and lead, together with a significant amount of copper, mustthereby have remained in the slag phase. The slag from the Vorstufe wasprocessed in subsequent step 1 to produce a black copper product to begranulated, together with another remaining slag phase. Step 2 producedfrom this slag phase a raw mixed tin product that was subsequentlypre-refined using silicon metal to produce a tin mixture and a siliconresidue. The last step yielded a final slag, also for granulation. Instep 2, it is assumed that all copper and nickel leaves the furnace withthe raw tin metal phase. The last reduction step yielded a final slag,also for granulation. It is not stated what happens to the metal phasefrom the last step, but it may be assumed that this metal remained inthe rotary drum furnace and the next load of smelter slag was added toit as the start of a new process cycle.

A first problem with the process of DE 102012005401 A1 is that theprocess produces in step 1 a black copper by-product, not suitable forrecovering the copper by electrorefining. This black copper thusrequires significant further processing, typically by extrapyrometallurgical steps. The process of DE 102012005401 A1 therefore hasa rather low overall recovery of tin. Significant amounts of tin remainin the black copper by-product and do not find their way into the rawtin product.

Another problem with the process of DE 102012005401 A1 is that step 2should produce a relatively rich raw mixed tin product. The raw tin isfurther pre-refined using silicon metal to remove metals other than tin.Silicon metal is a rather expensive ingredient, and the presence in theraw tin of metals other than tin should therefore be kept low in orderto keep the economics of the process acceptable. Producing in step 2 arich raw mixed tin product means that the slag from this step alsocontains high amounts of valuable metals.

Yet another problem with the process of DE 102012005401 A1 is that theseparation is also relatively poor in the last step, where most of thevaluable metals should be recovered that remained in the slag from thethird step in which the raw mixed tin was produced. In order to avoidunacceptably high loss of valuable metals in the final slag from thefinal reduction step, significant amounts of other metals need to bereduced in that step and be recycled to the start of the next batch inthe rotary drum furnace.

The process of DE 102012005401 A1 thus suffers from a difficult dilemmawith respect to the degree of reduction in the final step: eitherterminate early and suffer a high loss of valuable metals in the finalslag, or push through and suffer from a high amount of metals stayingbehind in the furnace after granulating the final slag.

There therefore remains a need for a process for the production of crudesolder product, preferably in combination with the production of refinedcopper product suitable for a subsequent electrorefining step, whichprocess would be more volume efficient and bring the advantages of ahigher purity solder product combined with a higher recovery of thevaluable metals tin, lead in the solder product. In co-production withcopper, also the refined copper is preferably of a higher purity.

The present invention aims to obviate or at least mitigate the abovedescribed problem and/or to provide improvements generally.

SUMMARY OF THE INVENTION

According to the invention, there is provided a process as defined inany of the accompanying claims.

In an embodiment, the invention provides a process for the production ofa crude solder composition comprising the provision of a first solderrefining slag which slag comprises significant amounts of tin and/orlead and at most 10.0% wt together of copper and nickel, the processfurther comprising the steps of

-   e) partially reducing the first solder refining slag, thereby    forming a first crude solder metal composition and a second solder    refining slag, followed by separating the second solder refining    slag from the first crude solder metal composition,-   f) partially reducing the second solder refining slag, thereby    forming a second lead-tin based metal composition and a second spent    slag followed by separating the second spent slag from the second    lead-tin based metal composition,    characterised in that a copper containing fresh feed is added to    step f), preferably before reducing the second solder refining slag.

The applicants have found that the addition of copper to step f), aspart of the copper containing fresh feed, brings the advantage that thiscopper almost entirely ends up in the metal phase formed in step f). Theapplicants have found that the extra copper in this metal phase of stepf) affects the equilibria for tin and lead between the slag and themetal phases at the end of step f), favouring the move of these soldermetals from the slag phase into the metal phase. The applicants havefound that this effect may be achieved without increasing theconcentration of copper in the spent slag obtained from step f) up toeconomically significant and possibly unacceptable levels. Theapplicants have found that the addition of copper to step f) allows toobtain a spent slag from step f) which contains only low concentrationsof tin and/or lead. This brings the advantage that the spent slag fromstep f) requires less further treatment, if any at all, for itsresponsible disposal or for its use in a suitable downstreamapplication.

The applicants have found that the second lead-tin based metalcomposition from step f) is a highly suitable stream for being recycledupstream of step e), to a process step from which products not only thesolder metals tin and/or lead, but also copper, may be recovered intosuitable prime products from the process.

The applicants have found that the present invention brings the benefitof a higher recovery of the valuable metals tin, lead, and asappropriate also copper and possibly nickel, into product streams inwhich their presence is desired. This also reduces the burden which maybe caused by the presence of these metals in product streams where theyare less or not desired. At the end of step e), the compositions of thefirst crude solder composition and the second solder refining slag areexpected to be in equilibrium. Allowing more of the solder metals in thesecond solder refining slag therefore allows to obtain a first crudesolder composition that is richer in the solder metals, and hencerequires less burdensome refining treatment as part of its furtherprocessing, in particular when this crude solder composition is used forrecovery of high purity metal streams, such as high purity tin and/orlead.

The applicants have found that the provision of the extra reduction stepf) for treating the second solder refining slag allows the recovery ofmost of the solder metals from that stream, and strongly reduces theamounts of solder metals that are lost with the second spent slagproduced in this extra reduction step f). The applicants have found thatthis additional recovery of valuable metals from the second solderrefining slag allows for obtaining a first crude solder metalcomposition that is richer in the desired solder metals, and henceleaner in the metals that are undesirable as part of the solder product,and which therefore should be removed. The removal of these other metalsfrom the crude solder metal composition requires chemicals, inparticular when the refining process comprises the treatment withsilicon metal, such as explained in DE 102012005401 A1 for treating theraw tin product. Obtaining a crude solder metal composition containingless undesirable other metals thus brings significant economic benefitsfor the downstream refining of that crude solder metal composition.

The applicants have further found, linked to a higher production ofcrude solder product from step e), and provided the second solderrefining slag is kept in the same furnace, that more furnace volumebecomes available for adding suitable fresh feeds to the furnace chargeof step f). The present invention therefore brings the advantage thatmore fresh feed may be processed as part of step f). More room for extrafresh feed in step f) means more room for additional copper, whichallows for an increased recovery of tin and/or lead in step f) and areduced presence of tin and/or lead in the spent slag from step f).

The applicants have found that step f) is also highly suitable foradding fresh feedstocks that contain appreciable amounts of metals thatare primarily present as oxides and which readily end up as part of thespent slag in step f), such as silicon, iron and aluminium. The benefitis that these components are, immediately as part of step f), removedfrom the process. Step f) may thus serve as a first rough refining ofsuitable fresh feedstocks to the overall process. The allowance of morefresh feed in step f) therefore allows to exploit this benefit on ahigher volume.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a process flowsheet of a process according to the presentinvention, starting from a black copper composition provided by anupstream smelter step, and leading to the production of at least onecopper product suitable for anode casting and at least one crude solderproduct.

DETAILED DESCRIPTION

The present invention will hereinafter be described in particularembodiments, and with possible reference to particular drawings, but theinvention is not limited thereto, but only by the claims. Any drawingsdescribed are only schematic and are non-limiting. In the drawings, thesize of some of the elements may be exaggerated and not drawn to scalefor illustrative purposes. The dimensions and the relative dimensions inthe drawings do not necessarily correspond to actual reductions topractice of the invention.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order. The terms are interchangeable under appropriatecircumstances and the embodiments of the invention can operate in othersequences than those described and/or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. The terms so used areinterchangeable under appropriate circumstances and the embodiments ofthe invention described herein may operate in other orientations thandescribed or illustrated herein.

The term “comprising”, as used in the claims, should not be consideredas being limited to the elements that are listed in context with it. Itdoes not exclude that there are other elements or steps. It should beconsidered as the presence provided of these features, integers, stepsor components as required, but does not preclude the presence oraddition of one or more other features, integers, steps or components,or groups thereof. Thus, the volume of “an article comprising means Aand B” may not be limited to an object which is composed solely ofagents A and B. It means that A and B are the only elements of interestto the subject matter in connection with the present invention. Inaccordance with this, the terms “comprise” or “embed” enclose also themore restrictive terms “consisting essentially of” and “consist of”. Byreplacing “comprise” or “include” with “consist of” these termstherefore represent the basis of preferred but narrowed embodiments,which are also provided as part of the content of this document withregard to the present invention.

Unless specified otherwise, all values provided herein include up to andincluding the endpoints given, and the values of the constituents orcomponents of the compositions are expressed in weight percent or % byweight of each ingredient in the composition.

Additionally, each compound used herein may be discussed interchangeablywith respect to its chemical formula, chemical name, abbreviation, etc.

In this document and unless specified differently, stream compositionsare represented on a weight basis, and relative to the total dry weightof the composition.

Within the context of the present invention, the terminology “at leastpartially” includes its endpoint “fully”. Relating to the degree towhich a particular oxidation or reduction step of the process isperformed, the preferred embodiment is typically a partial performance.Relating to an addition or recycle of a process stream into a particularprocess step, the preferred embodiment is typically the “fully”operating point within the range that is covered by the terms “at leastpartially”.

In this document and unless specified differently, amounts of metals andoxides are expressed in accordance with the typical practice inpyrometallurgy. The presence of each metal is typically expressed in itstotal presence, regardless whether the metal is present in its elementalform (oxidation state=0) or in any chemically bound form, typically inan oxidized form (oxidation state >0). For the metals which mayrelatively easily be reduced to their elemental forms, and which mayoccur as molten metal in the pyrometallurgical process, it is fairlycommon to express their presence in terms of their elemental metal form,even when the composition of a slag is given, wherein the majority ofsuch metals may actually be present in an oxidized form. It is thereforethat the composition of a slag in this document specifies the content ofFe, Zn, Pb, Cu, Sb, Bi as elemental metals. Less noble metals are moredifficult to reduce under non-ferrous pyrometallurgical conditions andoccur mostly in an oxidized form. These metals typically are expressedin terms of their most common oxide form. Therefore, slag compositionsare typically giving the content of Si, Ca, Al, Na respectivelyexpressed as SiO₂, CaO, Al₂O₃, Na₂O.

The applicants have found that the results of a chemical analysis of ametal phase is significantly more reliable than these of a slag phaseanalysis. Where in this document numbers are derived from a materialbalance over one or more process steps, the applicants prefer by far, ifpossible, to base such calculations on as much as possible metal phaseanalyses, and to minimise the use of slag analyses. For instance, theapplicants prefer to calculate the recovery of tin and/or lead in thefirst copper refining slag from step b) based on the amount of tinand/or lead in the combined feeds to step b) that is not anymoreretrieved in the first enriched copper metal phase from step b), ratherthan based on the tin and/or lead concentration reported for the firstcopper refining slag.

The applicants have further found that an analysis of a slag phase whichis further processed may often be corrected by making a mass balanceover the downstream process step or steps, and by back-calculating,using the amounts of the products obtained from the downstream step incombination with the analysis of these products, at least one preferablybeing a liquid metal product offering much more reliable analyticalresults. Such a back-calculation may be performed for several of therelevant particular metals individually, and may enable theestablishment of reliable material balances over most individual stepsof the process according to the present invention. Such aback-calculation may also be instrumental in determining the compositionof a liquid metal stream from which the obtaining of a representativesample may be highly challenging, e.g. a molten solder metal streamcontaining high amounts of lead together with tin.

The applicants prefer to use X-Ray Fluorescence (XRF) for analysing ametal phase in the context of the present invention. The applicantsprefer for this analysis to take a sample of the molten liquid metal,and the applicants prefer to use a sampler for instant analyticalpurposes in copper refining from the company Heraeus Electro Nite, whichresults quickly in a solid and cooled sample for further processing. Asurface of the cold sample is than suitably surface treated before theanalysis is performed by use of an XRF probe. The XRF analyticaltechnique however does not analyse for the level of oxygen in thesample. If needed, for establishing the complete composition of a metalphase including the oxygen content, the applicants therefore prefer toseparately measure the oxygen content of the metal in the molten liquidmetal present in the furnace, preferably by using a disposable one-timeelectrochemical sensor for batch processes in copper refining offered bythe company Heraeus Electro Nite. The analytical result of the metalphase analysis by XRF, as described above, may then be adjusted, ifdesired, for the oxygen content obtained from the separate oxygenanalysis. The compositions reported in the Example of this document havenot been adjusted for inclusion of their oxygen content.

The present invention is primarily concerned with the recovery of thetarget metals copper, nickel, tin and/or lead into product streamssuitable for deriving therefrom prime metal products of high purity. Theprocess according to the present invention comprises different processsteps and these process steps may be labelled as either an oxidationstep or a reduction step. With this label, the applicants want toaddress the chemical reactions which these target metals may be subjectto. A reduction step is thus comprising that at least one of thesetarget metals is being reduced from at least one of its correspondingoxides to its elemental metal form, with the intention to move thatmetal from the slag phase to the metal phase in the furnace. Such areduction step is preferably promoted by the addition of a reducingagent, as explained at several locations in this document. As reductionsteps qualify the process steps with references 400, 600, 700, 900, 1000and 1100. In an oxidation step, the main purpose is the conversion of atleast one of the target metals to at least one of its correspondingoxides, with the intention to move that metal from the metal phase tothe slag phase in the furnace. The oxygen for that conversion may in thecontext of the present invention be supplied from a variety of sources.The oxygen does not necessarily have to come from air or oxygen that maybe blown into the liquid bath. The oxygen may equally be supplied by theintroduction of a slag phase that was obtained from another process stepand in which the oxygen is bound in an oxide of at least one othermetal. An oxidation step in the context of the present invention maythus possibly be performed without any injection of air or oxygen. Asoxidation steps therefore qualify the process steps with references 100,200, 300, 500, 800 and 1200.

From the target metals which the present invention is recovering, Sn andPb are considered “the solder metals”. These metals distinguishthemselves from the other target metals copper and/or nickel becausemixtures containing major amounts of these metals usually have a muchlower melting point than mixtures containing major amounts of copperand/or nickel. Such compositions have been used already millennia agofor creating a permanent bond between two metal pieces, and this byfirst melting the “solder”, bringing it in place, and letting itsolidify. The solder therefore needed to have a lower meltingtemperature than the metal of the pieces it was connecting. In thecontext of the present invention, a solder product or a solder metalcomposition, two terms which are used interchangeably throughout thisdocument, mean metal compositions in which the combination of the soldermetals, thus the level of Pb plus Sn, represents the major portion ofthe composition, i.e. at least 50% wt and preferably at least 65% wt.The solder product may further contain minor levels of the other targetmetals copper and/or nickel, and of non-target metals, such as Sb, As,Bi, Zn, Al and/or Fe, and/or elements such as Si. In the context of thepresent invention, because the process is directed to the production ofa crude solder product and a copper product, the crude solder product orcrude solder metal composition obtained by the process in steps e)and/or n) is expected to also contain a measurable amount of at leastcopper, if only as an inevitable impurity.

In an embodiment of the present invention, the copper containing freshfeed comprises black copper and/or spent or reject copper anodematerial. The applicants have found that step f) is able to accommodatesignificant amounts of black copper obtainable from an upstream smelterstep. The present invention therefore brings the advantage that theoverall process, comprising the steps of the process according to thepresent invention, is able to process much higher amounts of blackcopper obtainable from an upstream smelter step.

The present invention brings the further advantage that in step f) thisblack copper already undergoes a first refining step and that the rejectmaterial in the black copper immediately and directly ends up in thesecond spent slag which is removed from the process. This rejectmaterial therefore does not need to occupy valuable furnace volume inany of the other process steps before it is able to leave the process.

The applicants have also found that step f) is also highly suitable forintroducing spent and/or reject copper anode material. The production ofhigh quality copper typically comprises an electrolysis step, in whichcopper dissolves from an anode into the electrolyte and re-deposits on acathode. The anode is typically not fully consumed and the anode isremoved as spent copper anode material from the electrolysis bath beforethe last copper thereof has been dissolved. The applicants have foundthat step f) is highly suitable for introducing such spent copper anodematerial. Copper anodes for such copper electrolysis step are typicallycast by pouring a suitable amount of molten anode quality copper into amould and letting the copper solidify upon cooling. For a goodfunctioning of the copper electrolysis, the anodes have to comply withfairly stringent dimensional and shape requirements. Non-compliantanodes are preferably not used but represent reject copper anodematerial. The applicants have found that step f) is also highly suitablefor introducing such reject copper anode material.

The applicants prefer to introduce the spent and/or reject copper anodematerial as a solid with little to no preheat. This brings the advantagethat the melting of this material consumes at least a part of the heatof reaction generated by the chemical reactions occurring in step f).

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at least 2.0% wt of tin andoptionally at most 20% wt of tin. Preferably the first solder refiningslag comprises at least 3.0% wt of tin, more preferably at least 3.5%wt, even more preferably at least 4.0% wt, preferably at least 4.5% wt,more preferably at least 5.0% wt, even more preferably at least 5.5% wt,preferably at least 6.0% wt, more preferably at least 6.5% wt, even morepreferably at least 7.0% wt, preferably at least 7.5% wt, morepreferably at least 8.0% wt, even more preferably at least 8.5% wt,preferably at least 9.0% wt, more preferably at least 9.5% wt, even morepreferably at least 10.0% wt, preferably at least 10.5% wt, morepreferably at least 11.0% wt of tin. The applicants have found that themore tin being present in the first solder refining slag, the more tinmay end up in the first crude solder metal composition. Because highpurity tin is a commercial product that enjoys a significant economicpremium, a higher amount of tin in the first crude solder metalcomposition allows for a higher volume of high purity tin that may berecovered therefrom.

Preferably the first solder refining slag in the process according tothe present invention comprises at most 19% wt of tin, more preferablyat most 18% wt, even more preferably at most 17% wt, preferably at most16% wt, more preferably at most 15% wt, even more preferably at most 14%wt, preferably at most 13% wt, more preferably at most 12% wt, even morepreferably at most 11% wt of tin. The applicants have found that thecompliance of the tin content with the specified upper limit brings theadvantage that room is left for other metals which may bring advantages.In particular the presence of significant amounts of lead in the firstsolder refining slag, a major part thereof ending up in the first crudesolder metal composition, brings the advantage that the crude soldermetal composition has a higher density, which is highly beneficial inseparations by gravity of the solder from other phases such as a slagphase or a dross, e.g. during further downstream refining of the crudesolder metal composition.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at least 9% wt of lead andoptionally at most 30% wt of lead. Preferably the first solder refiningslag comprises at least 10% wt of lead, more preferably at least 11% wt,even more preferably at least 12% wt, preferably at least 13% wt, morepreferably at least 14% wt, even more preferably at least 15% wt,preferably at least 16% wt, more preferably at least 17% wt, even morepreferably at least 18% wt of lead. The applicants have found that morelead in the first solder refining slag brings more lead in the firstcrude solder metal composition. More lead in this first crude soldermetal product brings process benefits downstream, when the first crudesolder metal product is subjected to refining process steps, such asneeded when the first crude solder metal product is the raw material forderiving higher purity tin and/or lead prime products, e.g. by vacuumdistillation. The applicants have also found that a higher lead presencemay bring processing benefits, such as more ready phase separations, invarious steps that may be operated as part of the conversion of thefirst crude solder metal product into higher purity tin and/or leadprime products.

Preferably the first solder refining slag in the process according tothe present invention comprises at most 28% wt of lead, more preferablyat most 26% wt, even more preferably at most 24% wt, preferably at most23% wt, more preferably at most 22% wt, even more preferably at most 21%wt, preferably at most 20% wt, more preferably at most 19% wt, even morepreferably at most 18% wt, preferably at most 17% wt, more preferably atmost 16% wt and even more preferably at most 15% wt of lead. Theapplicants have found that it is advantageous to limit the presence oflead in the first solder refining slag in the process according to thepresent invention below the prescribed limits, because this allows roomfor the presence of tin. Having more tin brings the advantage that moretin may find its way into the first crude solder metal composition andtherefore more high purity tin final product may be obtained therefrom.Because high purity tin is of high commercial value, this technicaladvantage represents also a high economic benefit.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at least 12% wt together of tin andlead and optionally at most 50% wt together of tin and lead. Preferablythe first solder refining slag comprises at least 13% wt together of tinand lead, more preferably at least 14% wt, even more preferably at least15% wt, preferably at least 16% wt, more preferably at least 17% wt,even more preferably at least 18% wt, preferably at least 19% wt, morepreferably at least 20% wt, even more preferably at least 21% wt,preferably at least 22% wt, more preferably at least 23% wt, even morepreferably at least 24% wt, preferably at least 25% wt, more preferablyat least 26% wt, even more preferably at least 27% wt, preferably atleast 28% wt, more preferably at least 29% wt, even more preferably atleast 30% wt together of tin and lead. The applicants have found thatthe more tin and lead being present in the first solder refining slag,the more tin and lead may end up in the first crude solder metalcomposition. Because high purity tin and lead are commercial productsthat enjoy significant economic premiums, a higher amount of tin andlead together in the first crude solder metal composition allows for ahigher volume of high purity tin and of high purity lead that may berecovered therefrom.

Preferably the first solder refining slag in the process according tothe present invention comprises at most 45% wt together of tin and lead,more preferably at most 40% wt, even more preferably at most 39% wt,preferably at most 38% wt, more preferably at most 36% wt, even morepreferably at most 34% wt, preferably at most 33% wt, more preferably atmost 32% wt, even more preferably at most 31% wt, preferably at most 30%wt, more preferably at most 29% wt, even more preferably at most 28% wt,preferably at most 27% wt, more preferably at most 26% wt, even morepreferably at most 24% wt together of tin and lead. The applicants havefound that it is advantageous to limit the presence of tin and leadtogether in the first solder refining slag in the process according tothe present invention below the prescribed limits, because this allowsroom for the presence of oxygen and of other metals that have under theprocess conditions a higher affinity for oxygen than copper, nickel, tinand lead. This is particularly valid for metals such as iron, aluminium,sodium, potassium, calcium and other alkali and earth-alkali metals, butalso for other elements such as silicon or phosphorus. These elementshaving a higher affinity for oxygen typically end up as part of thesecond spent slag obtained from step f), meaning they are removed fromthe process with a discard stream. As a result, these elements do notend up as contaminants in one of the prime metal products from theprocess, meaning these streams enjoy a higher purity in the desiredmetals. The higher tolerance for these elements having a higher affinityfor oxygen than copper, nickel, tin and lead, also widens the acceptancecriteria for the feedstocks to the process according to the presentinvention. These upstream steps are therefore allowed to accept muchmore low quality raw materials, which are more abundantly available ateconomically more attractive conditions.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at most 8.0% wt and optionally atleast 0.5% wt of copper. Preferably the first solder refining slagcomprises at most 7.0% wt, more preferably at most 6.0% wt, even morepreferably at most 5.0% wt, preferably at most 4.6% wt, more preferablyat most 4.3% wt, even more preferably at most 4.0% wt, preferably atmost 3.9% wt, more preferably at most 3.8% wt, preferably at most 3.7%wt, more preferably at most 3.6% wt, even more preferably at most 3.5%wt of copper. The applicants have found that having less copper in thefirst solder refining slag also reduces the copper content of the firstcrude solder metal composition obtained in step e), because the copperis typically also reduced in step e) and most of the copper ends up aspart of the resulting first crude solder metal composition. The firstcrude solder metal composition usually needs to be submitted to furtherpurification steps to reduce the presence of metals other than tin, leadand antimony in the crude solder metal, e.g. before this crude soldermetal composition becomes suitable for the recovery of high purity tinand/or lead products. This includes the removal of copper. Such atreatment may e.g. be with silicon metal as described in DE 102012005401A1. Silicon metal is a rather expensive process chemical, and thetreatment results in a silicon compound of the contaminant metal as aby-product that needs to be reworked or disposed of. The copperentrained in the first crude solder metal thus causes an increase ofconsumption of silicon metal in such a purification step. It is thusadvantageous to limit the copper in the first solder refining slag.

The crude solder metal composition that is obtained from the processaccording to the present invention, i.e. the first crude solder metalcomposition as obtained from step e) and/or the second crude soldermetal composition obtained from step n) as described further below, maybe further treated to remove more of its contaminants, in particularcopper. This may be performed by contacting the crude solder metalcomposition, as a molten liquid, with elemental silicon and/oraluminium, elements which bind under the operating conditions with Cu,Ni and/or Fe and form a separate silicide and/or aluminide alloy phase.The applicants prefer to use silicon and/or aluminium containing scrap.Preferably the added material further comprises Sn and/or Pb, becausethese metals are readily upgraded into the respective prime productswhen introduced at this process stage. Because of the typical presenceof Sb and As in the crude solder metal composition, the applicantsprefer to use silicon and to avoid aluminium, although this is usuallymore readily available and more reactive. This avoids the formation ofH₂S, a toxic gas, and more exothermic reactions in the treatment vessel,and also avoids that the resulting alloy phase by-product, in contactwith water, could generate stibine and/or arsine, highly toxic gasses.The applicants have found that the silicon feed for this treatment stepmay contain a limited amount of iron (Fe), readily more than 1% wt andreadily up to 5% wt or even up to 10% wt of Fe. The process may thus beoperated using Si products that are unacceptable for other siliconconsumers, such as reject material from the production line, and whichmay thus be more readily available. The applicants have found that theburden of processing this extra Fe, which also binds with Si, istypically readily compensated by the advantageous conditions for thesupply of the silicon source.

The applicants prefer to feed the silicon containing feed in a granularform, e.g. with a grain size of 2-35 mm, in order on the one hand tolimit losses by dust and surface oxidation, and on the other hand toprovide sufficient surface for the intended chemical reactions and toavoid sieve plugging in the feed hopper. A powder form of the siliconcontaining feed for this refining step is preferably injected into thetreatment step.

The applicants prefer to have the crude solder metal composition at atemperature of at least 800° C. before starting to add the siliconand/or aluminium. In this further treatment step with silicon, severalof the chemical reactions are exothermic, and the reactions with nickeland with iron are more strongly exothermic than the reaction withcopper. The applicants therefore prefer to push the reaction by addingmore silicon containing feed at least until the temperature in thereaction vessel starts reducing again, a point which indicates that Feand/or Ni are about exhausted and Cu starts reacting. The extra amountof Si to be added may then readily be determined based on the Cu contentof the crude solder metal composition, and hence is readily and fairlyaccurately predictable.

The applicants prefer to perform this silicon treatment in a so-called“shaking ladle”, i.e. a furnace that is moving horizontally following anelliptic path, because it combines a fairly intense mixing performancewith a limited exposure to oxygen in the atmosphere, and a limitedinvestment cost. If the feed to this treatment is rather cold for ashaking ladle, the treatment step is preferably performed in a top blownrotary converter (TBRC) because of the improved heating capabilities.

The applicants prefer to monitor the silicon addition by analysingsamples of the supernatant silicide phase for Ni and Si, and to addsufficient Si to avoid the formation of a 3^(rd) Cu and Sn containingphase upon cooling, which extra phase would retain Sn that morepreferably should end up in the treated crude solder product of thetreatment step.

The applicants prefer to operate this treatment step batchwise. Uponreaction completion, the applicants prefer to pour the entire reactorcontent into separating/tapping ladles for cooling, which results in thesolidification first of the supernatant alloy phase containing thecontaminants. The molten crude solder metal composition underneath maythen be drained or tapped, and the solid crust remaining in the ladlemay be recovered, as a product that may be called the “cupro phase”,preferably for recovering its metals of interest, preferably byrecycling this cupro phase into a suitable upstream pyrometallurgicalprocess step. The applicants prefer to pour the reactor content into theseparating/tapping ladles for cooling at a temperature of at most 950°C., because this extends the useful life of the ladles, preferably madeof cast steel. The applicants have found that the crust may readily beremoved from the separating/tapping ladle, preferably by simply turningthe ladle upside down, while the latter is still hot, which brings theadvantage that the ladle is readily available for the next campaign,avoiding the loss of time and heat in between two successive uses. Anempty separating ladle is preferably kept warm until its next use inorder to further extend its useful life time. During this heating, theempty ladle is preferably rested on its side in a preheating stand, aposition which allows for an easy operation for the overhead crane.

The recovered cupro phase is then preferably melted again, optionallywith the addition of extra Pb, such as Pb scrap material, and preferablyin a TBRC type of furnace, such that any solder that was entrapped inthe crust is caught into a Pb-rich metal phase which may be drained (andsolidified) for further processing. This “washing” of the cupro phasewith Pb may be repeated, because of the extra recovery of Sn that may beachieved, provided sufficient elemental Si is still present. Theapplicants believe that Sn is present in the cupro phase also as part ofan intermetallic compound formed with Cu. The added Pb is presumablyable to break this intermetallic compound. The Cu may then react to formits silicide with still available Si, and the released Sn may dissolvein the Pb-containing liquid phase.

Washing the cupro phase with Pb brings the advantage that more Sn isrecovered and this extra Sn ends up in a stream that is already on apath towards the recovery of a high purity tin product. Pb isparticularly suitable as washing material because, thanks to its highdensity, it is able to obtain a relatively rapid and clear separation ofthe metal phase from the washed solid cupro phase.

The washing liquid, i.e. molten Pb further containing the washed out Sn,may readily be introduced into the crude solder which is prepared forvacuum distillation as described in WO 2018/060202 A1, where it may beof use to bring the Pb/Sn ratio of that stream closer to its target foran optimised further processing.

The washed cupro phase may then be recycled at a number of upstreamprocess steps, with the purpose to recover its Cu and/or Ni contentand/or to bring energy by the strongly exothermic reaction whenremaining elemental silicon oxidizes to at least one of its oxides.Suitable steps, for recycling the washed cupro phase to, are the copperrefining steps b), h) and j), the slag processing step c), and theupstream smelter step, as defined elsewhere in this document. Theapplicants have found that the washed cupro phase may becomesufficiently lean in Sn and/or Pb such that it may be introduced intothe furnace where the first high-copper metal composition, which isremoved from the process after step l), may be prepared for being castinto copper anodes comprising impurities such as nickel.

Preferably the first solder refining slag comprises at least 1.0% wt ofcopper, more preferably at least 1.5% wt, even more preferably at least2.0% wt, preferably at least 2.5% wt, more preferably at least 3.0% wt,even more preferably at least 3.5% wt of copper. The applicants havefound that it is advantageous to tolerate some copper in the firstsolder refining slag and to stay above the lower limit as specified. Theapplicants have found that this is to the benefit of the upstreamprocess steps as well as to the benefit of the feedstocks that theseupstream process steps are able to accept. At these levels, a higherpresence of copper usually also means a higher presence of tin and/orlead, which may be highly advantageous. Both technical benefitsrepresent advantages that balance the burden brought by the presence ofcopper in the first solder refining slag, and as a result thereof, thepresence of copper in the first crude solder metal composition.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at most 4.0% wt and optionally atleast 0.2% wt of nickel, preferably at most 3.5% wt, more preferably atmost 3.0% wt, even more preferably at most 2.5% wt, preferably at most2.0% wt, more preferably at most 1.5% wt, even more preferably at most1.0% wt of nickel. The applicants have found that nickel behaves verysimilarly to copper in step e). The advantages of keeping the nickelcontent of the first solder refining slag within the prescribed limitsare therefore similar to those described for copper, or for copper andnickel together, elsewhere in this document. Preferably the first solderrefining slag comprises at least 0.20% wt of nickel, more preferably atleast 0.25% wt, even more preferably at least 0.30% wt, preferably atleast 0.35% wt, more preferably at least 0.40% wt, even more preferablyat least 0.45% wt of nickel. This brings the advantage that the upstreamprocess steps from which the first solder refining slag is obtained, isable to accept feedstocks that contain nickel. These feedstocks arebecause of their nickel content, less acceptable in other processes, andmay therefore be available more abundantly and at economically moreattractive conditions.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at most 10.0% wt together of copperand nickel, preferably at most 9.0% wt, more preferably at most 8.0% wt,even more preferably at most 7.0% wt, yet more preferably at most 6.0%wt, preferably at most 5.5% wt, more preferably at most 5.0% wt, evenmore preferably at most 4.5% wt, preferably at most 4.0% wt, morepreferably at most 3.5% wt, even more preferably at most 3.0% wttogether of copper and nickel. The applicants have found that loweramounts of copper and/or nickel in the first solder refining slag leavemore room for more readily oxidizable metals, such as iron, which havethe tendency to reduce the viscosity of the slag phase, which isbeneficial for a good quality and fast separation of the metal phase andthe slag phase in the furnace, particularly as part of step e).

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at least 10% wt and optionally atmost 30% wt of iron. Preferably the first solder refining slag comprisesat least 11% wt of iron, more preferably at least 12% wt, even morepreferably at least 13% wt, preferably at least 14% wt, more preferablyat least 15% wt, even more preferably at least 16% wt, preferably atleast 17% wt, more preferably at least 18% wt, even more preferably atleast 19% wt, preferably at least 20% wt, more preferably at least 21%wt, even more preferably at least 22% wt of iron. Preferably the firstsolder refining slag comprises at most 29% wt of iron, more preferablyat most 28% wt, even more preferably at most 27% wt, preferably at most26% wt, more preferably at most 25% wt, even more preferably at most 24%wt, preferably at most 23% wt, more preferably at most 22% wt, even morepreferably at most 21% wt, preferably at most 20% wt of iron. Theapplicants have found that iron is an advantageous reducing agent formetals having under the process conditions a lower affinity for oxygenthan iron, such as copper, nickel, tin and lead. The applicantstherefore prefer to have an iron presence in the first solder refiningslag in compliance with the specified limits because this allows anupstream process step to use significant amounts of iron as a reducingagent, which e.g. brings the advantage of making many of the upstreamprocess steps more energy efficient. Another advantage is that also theallowance criteria for feedstocks of these upstream process steps arerelaxed, which thus allows to accept feedstocks that may be moreabundantly available and at economically more attractive conditions.

In an embodiment of the process according to the present invention, thefirst solder refining slag comprises at least 0.003% wt of antimony,preferably at least 0.004% wt, more preferably at least 0.005% wt, evenmore preferably at least 0.010% wt, preferably at least 0.015% wt, morepreferably at least 0.020% wt, even more preferably at least 0.025% wt,preferably at least 0.030% wt, and optionally at most 0.200% wt,preferably at most 0.180% wt, more preferably at most 0.150% wt, evenmore preferably at most 0.100% wt of antimony, preferably at most 0.090%wt, more preferably at most 0.080% wt, even more preferably at most0.070% wt, preferably at most 0.060% wt, more preferably at most 0.050%wt, even more preferably at most 0.040% wt, yet more preferably at most0.030% wt of antimony. The applicants have found that also most of theantimony as part of the first solder refining slag is typically reducedas part of step e), and most of it ends up as part of the first crudesolder metal composition. The applicants have further found that anamount of antimony may be acceptable in the process steps performed onthe first crude solder metal composition, even when these have theobjective of recovering high purity tin and/or lead prime products. Theapplicants have found that an amount of antimony may be acceptable, andmay even be desirable, in some of these higher purity metal primeproducts. The applicants have however found that the capability toaccommodate antimony in these downstream processes is limited withrespect to the amount of lead that is present. The applicants thereforealso prefer to comply with the upper limits specified for antimony aspart of the first solder refining slag.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at least 65% wt togetherof tin and lead, preferably at least 67% wt, more preferably at least69% wt, even more preferably at least 70% wt, preferably at least 72%wt, more preferably at least 74% wt, preferably at least 75% wt, morepreferably at least 76% wt, even more preferably at least 77% wttogether of tin and lead. The applicants have found that a higher amountof tin and lead being present in the first crude solder metalcomposition allows for a higher volume of high purity tin and of highpurity lead that may be recovered therefrom, products that are of higheconomic value.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at least 5.0% wt of tin,preferably at least 7.5% wt, more preferably at least 10.0% wt, evenmore preferably at least 15.0% wt, preferably at least 17% wt, morepreferably at least 19% wt, even more preferably at least 20% wt,preferably at least 21% wt, more preferably at least 22% wt of tin. Theapplicants have found that the more tin being present in the first crudesolder metal composition, the higher the volume of high purity tin thatmay be recovered therefrom.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at least 45% wt of lead,preferably at least 47.5% wt, more preferably at least 50% wt, even morepreferably at least 52% wt, preferably at least 53% wt, more preferablyat least 54% wt, even more preferably at least 55% wt of lead. Theapplicants have found that the more lead being present in the firstcrude solder metal composition, the higher the volume of high puritylead that may be recovered therefrom, i.e. commercial products thatenjoy significant economic premiums. The lead further brings theadvantage, in any phase separations occurring downstream during thefurther processing of the first crude solder metal composition, that theliquid metal streams comprising the lead have a higher density andtherefore more readily separate by gravity from any supernatant slag ordross phase. A further advantage is that the feedstocks of the overallprocess are allowed to contain more lead, such that a wider variety offeedstocks become acceptable, bringing the benefit of a wider selectionof possible feedstocks, possibly including feedstocks that are moreabundantly available and at more attractive conditions.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at most 26.5% wt togetherof copper and nickel, preferably at most 25.0% wt, more preferably atmost 22.5% wt, even more preferably at most 20.0% wt, preferably at most17.5% wt, more preferably at most 16.0% wt, even more preferably at most15.5% wt together of copper and nickel. The applicants have found thathaving less copper and nickel in the first crude solder metalcomposition obtained in step e) is advantageous. The first crude soldermetal composition usually needs to be submitted to further purificationsteps to reduce the presence of metals other than tin, lead and antimonyin the crude solder metal composition, e.g. before this crude soldermetal composition becomes suitable for the recovery of high purity tinand/or lead products. This includes the removal of copper and nickel.Such a treatment may e.g. be with silicon metal as described in DE102012005401 A1. Silicon metal is a rather expensive process chemical,and the treatment results in silicon compounds of the contaminant metalsas by-product that needs to be reworked or disposed of. The copper andnickel that are entrained in the first crude solder metal thus cause anincrease of consumption of silicon metal in such a purification step. Itis thus advantageous to limit the copper and nickel in the first crudesolder metal composition in compliance with the prescribed upperlimit(s).

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at most 17.5% wt ofcopper, preferably at most 15% wt, more preferably at most 14% wt, evenmore preferably at most 13% wt, preferably at most 12% wt, morepreferably at most 11% wt of copper. For the reasons explained above forcopper and nickel together, the applicants prefer to limit the copper inthe first crude solder metal composition in compliance with theprescribed upper limit.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at most 9.0% wt ofnickel, preferably at most 7.0% wt, more preferably at most 5.0% wt,even more preferably at most 4.0% wt, preferably at most 3.0% wt, morepreferably at most 2.0% wt of nickel. For the reasons explained abovefor copper and nickel together, the applicants prefer to limit thenickel in the first crude solder metal composition in compliance withthe prescribed upper limit.

In an embodiment of the process according to the present invention, thefirst crude solder metal composition comprises at most 8% wt of iron,preferably at most 8.0% wt, more preferably at most 7.5% wt, even morepreferably at most 7.0% wt, preferably at most 6.5% wt, more preferablyat most 6.0% wt, even more preferably at most 5.5% wt, preferably atmost 5.0% wt, more preferably at most 4.5% wt, even more preferably atmost 4.0% wt, preferably at most 3.5% wt of iron. The applicants havefound that having less iron in the first crude solder metal compositionobtained in step e) is advantageous. The first crude solder metalcomposition usually needs to be submitted to at least one furtherpurification step to reduce the presence of metals other than tin, leadand antimony in the crude solder metal composition, e.g. before thiscrude solder metal composition becomes suitable for the recovery of highpurity tin and/or lead products. This includes the removal of iron. Sucha treatment may e.g. be with silicon metal as described in DE102012005401 A1. Silicon metal is a rather expensive process chemical,and the treatment results in a silicon compound of the contaminant metalas a by-product that needs to be reworked or disposed of. The iron thatis entrained in the first crude solder metal thus cause an increase ofconsumption of silicon metal in such a purification step. It is thusadvantageous to limit the iron in the first crude solder metalcomposition in compliance with the prescribed upper limit(s).

In an embodiment of the process according to the present invention, thesecond solder refining slag comprises at most 2.0% wt together of copperand nickel, preferably at most 1.5% wt, more preferably at most 1.0% wt,even more preferably at most 0.5% wt, preferably at most 0.45% wt, morepreferably at most 0.40% wt together of copper and nickel. Less copperand nickel in the second solder refining slag means that there is alsoless copper and nickel in the first crude solder metal composition,which at the end of step e) is in equilibrium with the second solderrefining slag. The advantages of having less copper and nickel in thesecond solder refining slag therefore include the advantages explainedelsewhere in this document with respect of having less copper and/ornickel in the first solder refining slag. In addition, this featurebrings the further benefit that less copper and nickel may end up in thesecond lead-tin based metal composition obtained in step f) and wouldneed to be recovered therefrom. Another advantage is that more furnacevolume becomes available for step f), allowing for a higher amount offresh feed to be introduced as part of step f).

In an embodiment of the process according to the present invention, thesecond solder refining slag comprises at most 8.0% wt and optionally atleast 1.0% wt together of tin and lead, preferably at most 7.0% wt, morepreferably at most 6.0% wt, even more preferably at most 5.0% wt,preferably at most 4.5% wt, more preferably at most 4.0% wt, even morepreferably at most 3.5% wt together of tin and lead. The applicants havefound that it is advantageous to limit the presence of tin and lead inthe second solder refining slag at the end of step e) because most ofthese amounts of tin and lead that need to be recovered in step f), endup in the second lead-tin based metal composition, and need to befurther processed for their recovery into prime high quality metalproducts. It is also important to recover tin and in particular leadupstream of producing the second spent slag in step f). Typically anytin and/or lead ending up in a spent slag represent a loss of valuablemetals from the process, and may impose further treatment before thespent slag may be disposed of, or be suitable for use in an economicallymore valuable application.

On the other hand, the applicants also prefer to have at least 1.5% wttogether of tin and lead in the second solder refining slag, preferablyat least 2.0% wt, more preferably at least 2.5% wt, even more preferablyat least 3.0% wt, preferably at least 3.5% wt. This brings the advantageof also having more tin and lead together in the first crude soldermetal composition, which at the end of step e) is expected to be inequilibrium with the second solder refining slag, and of which theadvantages have been explained elsewhere in this document.

In an embodiment of the process according to the present invention, thesecond lead-tin based metal composition comprises at least 60% wt andoptionally at most 90% wt together of copper and nickel, preferably atleast 65% wt, more preferably at least 68% wt, even more preferably atleast 70% wt, even more preferably at least 72% wt together of copperand nickel. The applicants have found that a high amount of copper andnickel together, in particular a high amount of copper, in the secondlead-tin based metal composition at the end of step f) is advantageous.The copper and also the nickel act in step f) as extracting agents forother valuable metals, in particular for tin and lead, and the phaseequilibrium of copper and nickel makes this feasible under the correctconditions without at the same time causing an unacceptably high loss ofcopper and/or nickel in the second spent slag.

On the other hand, the applicants prefer the second lead-tin based metalcomposition to comprise at most 85% wt, preferably at most 82% wt, morepreferably at most 80% wt, even more preferably at most 77.5% wt,preferably at most 75% wt together of copper and nickel. This leavesmore room for recovering tin and/or lead and reduce the loss of tinand/or lead in the spent slag from step f). The applicants have alsofound that compliance with this upper limit strongly reduces the loss ofvaluable metals, in particular of copper, in the spent slag at the endof step f).

In an embodiment of the process according to the present invention, thesecond lead-tin based metal composition comprises at least 12% wttogether of tin and lead, preferably at least 15% wt, more preferably atleast 17% wt, even more preferably at least 18% wt, preferably at least19% wt, more preferably at least 20% wt, even more preferably at least21% wt, preferably at least 22% wt together of tin and lead. Theapplicants have found that a minimum presence of metals other thancopper, such as a minimum presence together of tin and lead, in themetal phase at the end of step f) brings the advantage that less copperis lost in the second spent slag which is at the end of step f) inequilibrium therewith.

In an embodiment of the process according to the present invention, thesecond lead-tin based metal composition comprises at least 60% wt andoptionally at most 85% wt of copper, preferably at least 65% wt, morepreferably at least 67% wt, even more preferably at least 69% wt,preferably at least 70% wt, more preferably at least 71% wt of copper.The applicants have found that in particular a high amount of copper inthe second lead-tin based metal composition at the end of step f) isadvantageous. The copper acts in step f) as an extracting agent forother valuable metals, in particular for tin and lead, and the phaseequilibrium of copper makes this feasible under the correct conditionswithout at the same time causing an unacceptably high loss of copper inthe second spent slag.

On the other hand, the applicants prefer the second lead-tin based metalcomposition to comprise at most 82.5% wt, preferably at most 80% wt,more preferably at most 77.5% wt, even more preferably at most 75% wt,preferably at most 72.5% wt of copper. This leaves more room forrecovering tin and/or lead and reduce the loss of tin and/or lead in thespent slag from step f). The applicants have also found that compliancewith this upper limit strongly reduces the loss of valuable copper inthe spent slag at the end of step f).

In an embodiment of the process according to the present invention, thesecond spent slag comprises at most 2.5% wt together of tin and lead,preferably at most 2.0% wt, more preferably at most 1.5% wt, even morepreferably at most 1.00% wt, preferably at most 0.95% wt together of tinand lead.

In an embodiment of the process according to the present invention, thesecond spent slag comprises at most 2.0% wt together of copper andnickel, preferably at most 1.5% wt, more preferably at most 1.0% wt,even more preferably at most 0.75% wt, preferably at most 0.60% wttogether of copper and nickel.

In an embodiment of the process according to the present invention, thesecond spent slag comprises at most 2.0% wt of copper, preferably atmost 1.5% wt, more preferably at most 1.0% wt, even more preferably atmost 0.70% wt of copper.

The specified upper limits on the presence of copper, nickel, tin, leadand any combination of these metals together, each individually bringsthe benefit that the economic value of the amounts of the target metalsleaving the process with the second spent slag from step f) is keptlimited. It reduces the need or desire to provide extra process steps onthe second spent slag before this may be discarded, and thus offers thebenefit that fewer or possibly even no further treatment steps arenecessary before the second spent slag may be disposed of or before theslag is considered acceptable in an economically more attractiveapplication or end-use.

In the second spent slag of the process according to the presentinvention are retrieved most of the elements that under the processconditions have a higher affinity for oxygen than tin and/or lead and/orcopper and/or nickel. This is particularly valid for metals such aszinc, chromium, manganese, vanadium, titanium, iron, aluminium, sodium,potassium, calcium and other alkali and earth-alkali metals, but alsofor other elements such as silicon or phosphorus. Any of these elementsending up in the second spent slag are removed from the process, and donot occupy useful furnace volume as compared as when they would berecycled to an upstream process step.

In an embodiment of the process according to the present invention, stepf) comprises adding a third reducing agent to step f).

The applicants have found that the third reducing agent allows to drivethe result of reduction step f) towards the desired separation ofvaluable metals into the second lead-tin based metal composition andmaintaining rejectable metals into the second spent slag. The applicantshave found that the third reducing agent may be a gas such as methane ornatural gas, but may also be a solid or a liquid, such as carbon, ahydrocarbon, even aluminium or iron.

In an embodiment of the process according to the present invention, thethird reducing agent comprises, and preferably is, a metal having underthe process conditions a higher affinity for oxygen than tin, lead,copper and nickel, preferably iron metal, more preferably scrap iron.The applicants prefer to use iron, preferably scrap iron as the reducingagent, because of its high availability at economically very attractiveconditions. The applicants have found that the addition of the solidreducing agent may bring the additional benefit that the furnacerequires less additional heating in order to maintain or reach itsdesired temperature. The applicants have found that this benefit may besufficiently large such that additional heating by burning a fuel usingair and/or oxygen may be limited or even hardly required in order toreach the desired temperature. The applicants have further found thatthe step f) may further benefit from the addition of silica, asexplained elsewhere in this document.

The applicants prefer to add to step f) an amount of third reducingagent that is rich in iron, preferably as multimetal material, becausethis multimetal material is more readily available at more advantageousconditions than higher purity tin, higher purity copper or higher purityiron. Another suitable material may be electric motors, preferably suchmotors after use, because of their high contents of iron for the coresand copper for the windings. The applicants have found that the copperand/or tin may readily be kept in the metal phase and be kept frommoving into the slag phase, while any iron into this copper-containingfresh feed readily moves into the slag phase as iron oxide, while ithelps the chemical reduction of other metals that have under the processconditions a lower affinity for oxygen than iron.

In an embodiment of the process according to the present invention, stepe) comprises adding a second reducing agent to step e), preferably tothe first solder refining slag before reducing the first solder refiningslag. The applicants have further found that to perform the reduction instep e), in addition to the metal stream that may be added into step e)or as an alternative, a reducing agent may be added to step e). Theapplicants have found that the addition of the reducing agent assists inachieving the desired chemical reduction. The applicants have found thatthe second reducing agent may be a gas such as methane or natural gas,but may also be a solid or a liquid, such as carbon, a hydrocarbon, evenaluminium or iron.

In an embodiment of the process according to the present invention, thesecond reducing agent comprises, and preferably is, a metal having underthe process conditions a higher affinity for oxygen than tin, lead,copper and nickel, preferably the second reducing agent comprises ironmetal, more preferably scrap iron. The applicants prefer to use iron,preferably scrap iron as the reducing agent, because of its highavailability at economically very attractive conditions. The applicantshave found that the addition of the solid reducing agent may bring theadditional benefit that the furnace requires less additional heating inorder to maintain or reach its desired temperature. The applicants havefound that this benefit may possibly be sufficiently large thatadditional heating by burning a fuel using air and/or oxygen may belimited or even hardly be required in order to reach the desiredtemperature. The applicants have further found that the step e) mayfurther benefit from the addition of silica, as explained elsewhere inthis document.

In an embodiment of the process according to the present invention, afirst Pb and/or Sn containing fresh feed is added to step e), preferablyto the first solder refining slag before reducing the first solderrefining slag, preferably the first Pb and/or Sn containing fresh feedcomprising and more preferably primarily being dross obtained fromdownstream processing of concentrated streams of Pb and/or Sn.

The applicants have found that step e) is also a very suitable locationin the process for introducing materials that are rich in tin and/orlead, yet poor in copper and nickel, but which may contain metals whichunder the process conditions have a higher affinity for oxygen than tinand lead. Their addition to step e) brings the advantage that the tinand/or lead are readily recovered as part of the first crude soldermetal composition, and are withdrawn from the process, while theso-called “less noble” metals have a short and straight process pathwayinto the second spent slag produced in the downstream step f).

The applicants have found that step e) is very suitable for recoveringtin and/or lead, and optionally antimony and/or arsenic, in rawmaterials or process by-products that are rich in such metals yetrelatively low in copper and/or nickel. The applicants have found thatthe first Pb and/or Sn containing fresh feed may further contain metalshaving under the process conditions a higher affinity for oxygen thantin and/or lead, such as sodium, potassium, calcium. Such metals maye.g. be introduced as part of process chemicals used in downstream stepsfor refining a tin and/or lead rich stream such as the first crudesolder metal composition or a downstream derivative. The applicants havefound that step e) is very suitable for recovering valuable metals froma dross by-product formed in one of the refining steps performed as partof the processes disclosed in WO 2018/060202 A1 or similar. Such drossby-product streams typically entrain economically significant amounts oftin and/or lead, but also contain the other metals that may have beenintroduced as part of process chemicals.

In an embodiment the process according to the present invention furthercomprises the step of

-   d) producing the first solder refining slag by partially oxidizing a    first liquid bath comprising copper and at least one solder metal,    thereby forming a first dilute copper metal composition and the    first solder refining slag, followed by separating the first solder    refining slag from the first dilute copper metal composition.

The applicants have found that the generation in step d) of a dilutecopper metal composition offers a major advantage in obtaining arelatively clear separation between on the one hand copper into a highpurity copper stream, potentially even up to anode quality, and on theother hand a crude solder stream such as the first crude solder metalcomposition obtained in step e). Any elemental copper in step d) acts instep d) as an extracting agent for the tin and/or lead, but alsoupstream. The copper therefore acts as a carrier for the tin and/orlead. It is therefore advantageous to have in the step d) and upstreamsome copper, because this in the first place helps in extracting moretin and/or lead and route it to step d).

The applicants have found that the oxidation step d), thanks to theproduction of the first dilute copper metal composition as the metalphase, is able to produce a first solder refining slag which is richerin tin and/or lead, particularly in tin and lead together, relative tothe amount of copper that is entrained with that first solder refiningslag. Because the first solder refining slag is enriched in tin and/orlead, this facilitates the downstream recovery of the solder metals(i.e. tin and/or lead) from this first solder refining slag in step e).

The applicants have found that the generation of the first dilute coppermetal composition in step d) also offers the further advantage that moretin and/or lead may be introduced with the raw materials to the overallprocess. This significantly widens the acceptability criteria for anyraw materials that additionally may be fed to step d) and upstream. Thisfeature thus significantly widens the acceptability criteria for the rawmaterials that are used in the production of the feeds to step d), someof them may be obtained as the main product from a smelter step. Thesmelter step is therefore allowed to accept much more low quality rawmaterials, which are more abundantly available at economically moreattractive conditions.

The applicants have further found that the generation of the firstdilute copper metal composition in step d) brings the further advantagethat in step d) a better separation may be obtained between the copperand nickel intended to go into the first dilute copper metalcomposition, and the tin and lead intended for going into the firstsolder refining slag.

In an embodiment the process according to the present invention furthercomprises the step of

-   c) partially reducing a first copper refining slag thereby forming a    first lead-tin based metal composition and a first spent slag,    followed by separating the first spent slag from the first lead-tin    based metal composition, the first lead-tin based metal composition    forming the basis for the first liquid bath.

The applicants have found that a slag obtained from copper refiningrepresents a highly suitable feedstock for obtaining by means of apartial reduction such as in step c) a metal composition that containscopper together with at least one solder metal selected from tin andlead and which metal composition is highly suitable for forming thebasis for the first liquid bath as feedstock for partial oxidation stepd). The reason for this is that a slag obtained from the metallurgicalrefining of copper contains copper together with at least one of thesolder metals tin and lead, typically with both tin and lead. Theapplicants have found that most of the copper, which is coming with thefirst copper refining slag, in step c) will end up as part of the firstlead-tin based metal composition forming in step c). The copper endingup in the first lead-tin based metal composition helps as a solvent forthe tin and/or lead present in process step c). The copper present instep c) thus helps keeping the tin and/or lead in the metal phase ofstep c), i.e. the first lead-tin based metal composition, and reducesthe amounts of tin and/or lead that may find their way into the firstspent slag from step c), and thus may be lost from the process.

The applicants have further found that the inclusion of step c) in theprocess according to the present invention brings several additionalbenefits.

In step c) may selectively be reduced those metals in the furnace havingunder the process conditions a lower affinity for oxygen, into theirrespective metals. These reduced metals may then be separated off as aliquid metal phase, the separation leaving a liquid slag phase that isless concentrated in those metals, but still contains metals andelements that have a higher affinity for oxygen. The purpose of thisstep is preferably to selectively recover most of the copper from thefirst copper refining slag as copper metal, together with as much aspossible of the tin and/or lead present. The reduction in step c) isthus preferably operated such that the first spent slag comprises atmost 20% wt total of copper, tin and lead together. Preferably, thefirst spent slag comprises less than 20% wt total of copper, tin andlead together, more preferably even much less. Highly preferably theamounts of copper, tin and/or lead in this slag are sufficiently lowsuch that they would not anymore represent an economically significantvalue. Most preferably, the concentrations of copper, tin and/or leadare sufficiently low such that the first spent slag would not causeenvironmental concerns when being disposed of as such, or may beacceptable for disposal after only limited further treatment.

In the first spent slag of step c) are preferably retrieved most of theelements that under the process conditions have a higher affinity foroxygen than tin and/or lead. This is particularly valid for metals suchas iron, aluminium, sodium, potassium, calcium and other alkali andearth-alkali metals, but also for other elements such as silicon orphosphorus.

The applicants have found that step c) preferably produces a firstlead-tin based metal composition that is highly suitable for furtherprocessing, in particular for producing a crude solder metal compositionthat may have commercial value by itself and/or be suitable for recoveryof tin and/or lead products of higher and commercially acceptablepurity.

The applicants have surprisingly found that it is possible in step c) toobtain a fairly clear separation between the valuable metals copper,nickel, tin and lead in the metal phase, and lower value metals such asiron and aluminium, and other elements such as silicon in the slagphase. This allows for a very high recovery of the valuable metals whileproducing a slag phase that is very low in these metals and hence may bediscarded, either directly or with relatively minor further treatment.The applicants believe that this clear separation is possible becausethe presence of copper in step c) as part of the overall furnace contentis within a particular concentration window. On the one hand, the copperacts as an extracting agent for tin and lead from the slag phase. On theother hand, the copper presence is sufficiently low such that the lossof copper in the slag phase is very limited.

Another major advantage is that the process according to the presentinvention including step c) has become much more tolerant to elementsother than copper, most of which being elements that have under theprocess conditions a higher affinity for oxygen than copper, tin andlead, and hence end up as part of the first spent slag. Thissignificantly widens the acceptability criteria for any raw materialsthat may additionally be fed to step b), a step which is introducedfurther below in this document, i.e. besides the black copper providedas part of step a), a step which is also introduced further below. Inaddition, this also significantly relaxes the acceptance criteria forthe black copper itself. This feature thus significantly widens theacceptability criteria for the raw materials that are used in theproduction of the black copper, usually in a smelter step. The smelterstep is therefore allowed to accept much more low quality raw materials,which are more abundantly available at economically more attractiveconditions.

Yet another advantage is caused by that the removal of the slag from thefurnace as part of that step b) liberates a significant part of thefurnace volume, such that in the further processing of the firstenriched copper metal phase obtained from step b), which usually isperformed in the same furnace, extra room is created for introducingfurther extra raw materials.

The applicants have found that this further processing of the firstlead-tin based metal composition from step c) may be operated much moreeffectively and also much more efficiently thanks to the upstreamremoval from the process, as part of the first spent slag, of at least asignificant part of the metals and elements having under the processconditions a high affinity for oxygen. The applicants have found thatthis feature of the process brings significant benefits downstream ofstep b), in the processing of the first lead-tin based metalcomposition.

One major advantage is that the volume of material to be processeddownstream is significantly reduced by the removal in step c) of asignificant amount of material as the first spent slag, i.e. before therecovery of the solder metals (Sn and/or Pb). In further downstreamsteps, this material would be deadweight and bring primarily drawbacksrather than benefits. In the process according to the present inventionincluding step c), the further processing of the first lead-tin basedmetal composition may be operated much more volume efficiently, meaningthat either smaller equipment may be used, or the process according tothe present invention creates opportunities for processing additionalstreams for which the known processes would have less or no room. Inaddition, energy consumption may be also reduced in these downstreamprocess steps, because of the reduced volume of hot material that needsto be processed.

The applicants have further surprisingly found that, by removing thefirst spent slag from the process according to the present inventionincluding step c), the separations in the pyrometallurgical processsteps downstream, particularly for processing the first lead-tin basedmetal composition, are also much improved. By having more clearseparations between the respective metal phases and their correspondingslag phases, the downstream recovery of valuable metals may be operatedmore effectively and more efficiently, i.e. with higher prime productyields, lower discards of valuable metals, and requiring lower energyinput, e.g. because of lower recycle stream volumes.

A further advantage of the process according to the present inventionincluding step c), is that in the further processing of the firstlead-tin based metal composition, extra materials may be introducedthanks to the extra furnace space made available by the removal of thehigh volume of the first spent slag from the process. Such extramaterials may e.g. be rich in tin and/or lead. Such extra materials maye.g. be process slags and/or drosses generated as by-products fromdownstream refining steps as part of the further purification of tinand/or lead streams into commercially valuable prime products.

Another and major advantage of the process according to the presentinvention including step c) is that it allows for a much higher amountof crude solder co-product for the same amount of copper that is beingprocessed. The applicants have found that the crude solderco-production, relative to the amount of copper being processed in thefirst copper refining step, may be increased by about 29% when comparedto the amounts obtained in the process described in U.S. Pat. No.3,682,623. The economic value of crude solder, particularly as apossible intermediate for the production of a high purity tin product,is highly significant relative to the value of the anode copper primeproduct which may be obtained from the black copper. The increase in therelative amount of crude solder co-product relative to the amount ofcopper that is processed in the first copper refining step, thereforebrings a significant economic advantage to the operator of the processaccording to the present invention.

In an embodiment of the process according to the present inventionincluding step c), step c) comprises adding a first reducing agent tostep c), preferably by adding it to the first copper refining slagbefore reducing the first copper refining slag. The applicants havefound that the addition of the reducing agent assists in achieving thedesired chemical reduction. The applicants have found that the firstreducing agent may possibly be a gas, such as methane or natural gas,but may also be a solid or a liquid, such as carbon, a hydrocarbon, evenaluminium or iron.

In an embodiment of the process according to the present inventionincluding step c), the first reducing agent comprises, and preferablyis, a metal having under the process conditions a higher affinity foroxygen than tin, lead, copper and nickel, preferably iron metal, morepreferably scrap iron. The applicants prefer to use iron, preferablyscrap iron as the reducing agent, because of its high availability ateconomically very attractive conditions. The applicants have found thatthe addition of the solid reducing agent may bring the additionalbenefit that the furnace requires less additional heating in order tomaintain or reach its desired temperature. The applicants have foundthat this benefit may be sufficiently large that additional heating byburning a fuel using air and/or oxygen may hardly be required in orderto reach the desired temperature. The applicants have further found thatstep c) may further benefit from the addition of silica, as explainedelsewhere in this document.

In an embodiment of the process according to the present inventionincluding step c), the total feed to step c) comprises at least 29.0% wtof copper, preferably at least 30.0% wt, more preferably at least 31.0%wt, even more preferably at least 32.0% wt, yet more preferably at least33.0% wt, preferably at least 34.0% wt, more preferably at least 35.0%wt, even more preferably at least 36.0% wt, preferably at least 37.0%wt, more preferably at least 38.0% wt of copper.

In an embodiment of the process according to the present inventionincluding step c), the total feed to step c) comprises an amount ofcopper that is at least 1.5 times as high as the total amount of soldermetals present, i.e. the sum of Sn plus Pb, preferably at least 1.6times, more preferably at least 1.7 times, even more preferably at least1.8 times, yet more preferably at least 1.9 times, preferably at least2.0 times, more preferably at least 2.1 times as high as the totalamount of solder metals present.

The applicants have found that the prescribed amount of copper bringsthe advantage that there is sufficient copper present to act as asolvent for extracting solder metals from the slag phase into the firstlead-tin based metal composition, and hence improves the recovery ofvaluable tin and/or lead from the slag in step c). The applicants havefound that this advantage may be obtained without bringing along anunacceptable loss of valuable copper in the slag phase that is formed instep c).

The applicants have found that the lower limit specified for thepresence of copper, relative to the presence of the sum of Sn plus Pbpresent, in the total feed to step c) brings the advantage that a betterextraction of Sn and Pb is obtained from the slag phase, and thiswithout introducing significant amounts of copper in the slag phase. Theapplicants have found that the high presence of copper in the feed tostep c) affects the equilibria for tin and lead between the slag and themetal phases at the end of step c), favouring the move of these soldermetals from the slag phase into the metal phase. The applicants havefound that this effect may be achieved without increasing theconcentration of copper in the spent slag obtained from step c) up toeconomically significant and possibly unacceptable levels. Theapplicants have found the high amount of copper in the feed to step c)allows to obtain a spent slag from step c) which contains only lowconcentrations of tin and/or lead, as well as copper. This brings theadvantage that the spent slag from step c) requires less furthertreatment, if any at all, for its responsible disposal or for its use ina suitable downstream application.

In an embodiment of the process according to the present inventionincluding step c), the first spent slag from step c) comprises at most20% wt and even better at most 18% wt total of copper, tin and leadtogether, preferably at most 15% wt, more preferably at most 12% wt,even more preferably at most 9.0% wt, yet more preferably at most 7.0%wt, preferably at most 5.0% wt, more preferably at most 4.0% wt, evenmore preferably at most 3.0% wt, yet more preferably at most 2.0% wt,preferably at most 1.5% wt and more preferably at most 1.10% wt total ofcopper, tin and lead together.

In an embodiment of the process according to the present inventionincluding step c), the first spent slag from step c) comprises at most7.0% wt of copper, preferably at most 5.0% wt, more preferably at most3.0% wt, even more preferably at most 2.0% wt, yet more preferably atmost 1.50% wt, preferably at most 1.00% wt, more preferably at most0.75% wt, even more preferably at most 0.60% wt, yet more preferably atmost 0.50% wt, preferably at most 0.40% wt of copper.

In an embodiment of the process according to the present inventionincluding step c), the first spent slag from step c) comprises at most7.0% wt of tin, preferably at most 5.0% wt, more preferably at most 3.0%wt, even more preferably at most 2.0% wt, yet more preferably at most1.50% wt, preferably at most 1.00% wt, more preferably at most 0.75% wt,even more preferably at most 0.60% wt, yet more preferably at most 0.50%wt, preferably at most 0.40% wt, more preferably at most 0.30% wt oftin.

In an embodiment of the process according to the present inventionincluding step c), the first spent slag from step c) comprises at most7.0% wt of lead, preferably at most 5.0% wt, more preferably at most3.0% wt, even more preferably at most 2.0% wt, yet more preferably atmost 1.50% wt, preferably at most 1.00% wt, more preferably at most0.75% wt, even more preferably at most 0.60% wt, yet more preferably atmost 0.50% wt, preferably at most 0.40% wt of lead.

The specified upper limits on the presence of copper, tin, lead and ofthe three metals together in the first spent slag, each individuallybrings the benefit that the economic value of the amounts of the threetarget metals leaving the process with the first spent slag from step c)is kept limited. It reduces the need or desire to provide extra processsteps on the first spent slag before this may be discarded, and thusoffers the benefit that fewer or possibly even no further treatmentsteps are necessary before the first spent slag may be disposed of orbefore the slag is considered acceptable in an economically moreattractive application or end-use.

In the first spent slag of the process according to the presentinvention comprising step c) are retrieved most of the elements thatunder the process conditions have a higher affinity for oxygen than tinand/or lead and/or copper and/or nickel. This is particularly valid formetals such as zinc, chromium, manganese, vanadium, titanium, iron,aluminium, sodium, potassium, calcium and other alkali and earth-alkalimetals, but also for other elements such as silicon or phosphorus.

In an embodiment, the process according to the present invention furthercomprises the steps of

-   a) providing a black copper composition comprising a significant    amount of copper together with a significant amount of tin and/or    lead,-   b) partially oxidizing the black copper composition, thereby forming    a first enriched copper metal phase and the first copper refining    slag, followed by separating the first copper refining slag from the    first enriched copper metal phase, and feeding the first copper    refining slag to step c).

The applicants have found that the partial oxidation of a black copperfeedstock is highly effective for the production of a slag phase, i.e.the first solder refining slag, which slag is particularly suitable forthe derivation of a crude solder stream, such as the first crude soldermetal composition of step e), which crude solder stream may serve as anintermediate for the recovery of high purity tin and/or lead products.The applicants have found that this effectiveness is particularly due tothe obtaining, in step d), of the first dilute copper metal composition,but also because of the sequence of oxidation and reduction steps asspecified in the process according to the present invention includingsteps a), b), c) and d).

In an embodiment of the process according to the present inventioncomprising step b), the recovery of tin in step b) as part of the firstcopper refining slag, relative to the total amount of tin present instep b), is at least 20%, preferably at least 30%, more preferably atleast 40.00%, even more preferably at least 45%, yet more preferably atleast 50%, preferably at least 55%, more preferably at least 57%. Nounits need to be specified for the % recovery of a particular element,because regardless whether one considers atoms or weight, the % recoveryremains the same.

In an embodiment of the process according to the present inventioncomprising step b), the recovery of lead in step b) as part of the firstcopper refining slag, relative to the total amount of lead present instep b), is at least 20%, preferably at least 30.00%, more preferably atleast 40%, even more preferably at least 45%, yet more preferably atleast 50%, preferably at least 55%, more preferably at least 60%.

The specified lower limit on the recovery of tin and/or lead in step b)as part of the first copper refining slag brings the advantage thatalready in the first oxidation step which is performed on the blackcopper, a significant amount of the tin and/or lead present is removed,together with significant amounts of other elements other than copper.This brings the advantage that less impurities are fed to the stepsperformed downstream on the first enriched copper metal phase. Thismeans that the downstream process steps on the first enriched coppermetal phase have to cope with a lower amount of impurities, and alsowith less volume occupancy by the first enriched copper metal phase.This usually means that more precious furnace volume is liberated in thesubsequent processing steps performed on the first enriched copper metalphase, which opens room for introducing extra material in these processsteps, and hence the opportunity for an increased production of finalcopper product within the same furnace volume constraints. The listedadvantages are associated with the lower limit on the recovery of tin instep b), also with the lower limit on the recovery of lead in step b),and on a combination of a lower limit on the recovery of tin with alower limit on the recovery of lead in step b). The effects arecumulative with respect to the two metals tin and lead, and togetherbring even an enhanced effect relative to the sum of the two individualeffects.

The applicants have found that the desired recoveries in step b) may beobtained by controlling the presence of oxygen and/or oxygen donors instep b) within appropriate limits, if needed combined with a controlledaddition of scavengers for oxygen, and the addition of flux material.

In an embodiment of the process according to the present invention,extra raw materials are added as fresh feed to step b). The applicantsprefer to add raw materials containing solid metal because the meltingof this solid metal is able to absorb a part of the reaction heat andassists in keeping the temperature of the furnace within the preferredrange. The applicants prefer to use for this purpose raw materials thatare rich in copper and which may contain at least minor amounts of Snand/or Pb. The preferred temperature range is delimited by a lower limitbelow which the viscosity of at least one of the liquid phases becomesexcessively high for the furnace to operate. The preferred temperaturerange is delimited by an upper limit above which the volatility ofvaluable metals, in particular of tin and/or lead, becomes excessive andthe recovery of these metals as part of the furnace dust becomesexcessively troublesome, complex and expensive.

In an embodiment of the process according to the present inventionincluding step a), the black copper composition complies with at leastone and preferably all of the following conditions:

-   -   comprising at least 50% wt of copper,    -   comprising at most 96.9% wt of copper,    -   comprising at least 0.1% wt of nickel,    -   comprising at most 4.0% wt of nickel,    -   comprising at least 1.0% wt of tin,    -   comprising at most 15% wt of tin,    -   comprising at least 1.0% wt of lead,    -   comprising at most 25% wt of lead,    -   comprising at most 3.5% wt of iron, and    -   comprising at most 8.0% wt of zinc.

The applicants prefer that any black copper which may be used in theprocess according to the present invention, i.e. also any black copperused in a process step other than step b) complies with at least one ofthe above conditions, and preferably with all.

In an embodiment of the process according to the present invention, theblack copper comprises at most 96.9% wt or better at most 96.5% wt ofcopper, preferably at most 96.0% wt, more preferably at most 95.0% wt,even more preferably at most 90.0% wt, yet more preferably at most 85.0%wt, preferably at most 83.0% wt, more preferably at most 81.0% wt, evenmore preferably at most 80.0% wt, yet more preferably less than 80.0% wtand preferably at most 79.0% wt of copper. It brings the advantage thatthe upstream process for producing the black copper may accept rawmaterials comprising much more metals other than copper. It isparticularly advantageous to accept more tin and/or lead in theproduction of the black copper, and these higher amounts of tin and/orlead may readily be processed into an increased amount of crude solderco-product, a product that is having a relatively high economic value.

In an embodiment of the process according to the present invention, theblack copper comprises at least 50% wt or even better 51% wt of copper,preferably at least 52% wt, more preferably at least 53% wt, even morepreferably at least 54% wt, yet more preferably at least 55% wt,preferably at least 57% wt, more preferably at least 59% wt, even morepreferably at least 60% wt, yet more preferably at least 62% wt,preferably at least 64% wt, more preferably at least 66% wt, even morepreferably at least 68% wt, yet more preferably at least 70% wt,preferably at least 71% wt, more preferably at least 72% wt, even morepreferably at least 73% wt, yet more preferably at least 74% wt,preferably at least 75% wt, more preferably at least 77.5% wt, even morepreferably at least 80% wt, yet more preferably at least 85% wt ofcopper.

This brings the advantage that a pre-refining step, such as provided inU.S. Pat. No. 3,682,623 for upgrading a black copper containing 75-80%wt of copper to about 85% wt of copper or higher (85.12% wt of copper inthe Example, Table VI), may be dispensed with.

The applicants have further found that the overall process is moreoperable and efficient, and usually produces more of the prime products,if the copper concentration in the black copper stays within theprescribed lower limit. With a lower copper concentration in the blackcopper, other elements make up the balance. This is quite acceptable andoften even desirable if it are valuable metals that make up the balance,such as lead, but even more interestingly when also including tin. Thesemetals consume chemicals during any oxidation and/or reduction step, butultimately a major part thereof ends up in a prime product stream. If,however and on the contrary, it are lower value metals or elements whichinevitably end up in one of the spent process slags that make up thebalance, then the lower copper concentration is rather disadvantageousbecause these metals and/or elements consume chemicals in the oxidationsteps as part of the copper refining steps, and/or may consume otherchemicals in one of the downstream reduction steps, such as step c) ofthe process according to the present invention. In addition, these lowvalue metals or elements take up volume in the furnace, and theirpresence therefore demands bigger furnaces and hence a higher investmentcost. Within a given available equipment size, the presence of thesemetals or elements tightens the restrictions on introducing into any ofthe process steps higher value raw materials such as those containinghigh concentrations of copper, tin and/or lead. The black coppercomposition is typically an intermediate produced by anotherpyrometallurgical process step, i.e. a smelter step. A smelter stepresults in a molten metal product, the so-called “black copper”, and aliquid slag of primarily metal oxides, usually in the presence ofsignificant amounts of silica. The applicants prefer in a smelter stepto obtain a black copper product having at least the minimum amount ofcopper as specified, because the high copper presence acts as anextracting agent for other valuable metals, e.g. tin and lead. Keepingthe copper concentration in the black copper composition above thespecified limit therefore results in a higher recovery of these othervaluable metals present in the black copper composition, rather thanlosing these valuable metals as part of the smelter slag, in which thesemetals typically have little to no value and even may represent aburden.

In an embodiment of the process according to the present invention, theblack copper comprises at least 1.0% wt of tin, preferably at least 1.5%wt, more preferably at least 2.0% wt, even more preferably at least 2.5%wt, yet more preferably at least 3.0% wt, preferably at least 3.5% wt,more preferably at least 3.75% wt, even more preferably at least 4.0%wt, yet more preferably at least 4.5% wt, preferably at least 5.0% wt,more preferably at least 5.5% wt, even more preferably at least 6.0% wt,yet more preferably at least 6.5% wt, preferably at least 7.0% wt, morepreferably at least 7.5% wt, even more preferably at least 8.0% wt, yetmore preferably at least 8.5% wt, preferably at least 9.0% wt, morepreferably at least 9.5% wt, even more preferably at least 10.0% wt, yetmore preferably at least 11.0% wt of tin. Tin is a highly valuable metalwhich is in its higher purity product form rather scarcely available.The applicants therefore prefer to produce as much tin as their processis able to handle. In addition, the applicants prefer to recover thistin from raw materials of low economic value, in which tin is typicallypresent in low concentrations. Such low value raw materials oftencontain high amounts of elements that are difficult to process in apyrometallurgical copper refining process, and therefore are usuallyfirst processed in a smelter step. The tin in those low value rawmaterials therefore mainly ends up as part of the black coppercomposition. The applicants prefer to process as much tin as possiblefrom such low value raw materials, and hence prefer to have the blackcopper composition of the process according to the present inventioncontain as much tin as possible within the other process constraints.

In an embodiment of the process according to the present invention, theblack copper comprises at least 1.0% wt of lead, preferably at least1.5% wt, more preferably at least 2.0% wt, even more preferably at least2.5% wt, yet more preferably at least 3.0% wt, preferably at least 3.5%wt, more preferably at least 3.75% wt, even more preferably at least4.0% wt, yet more preferably at least 4.5% wt, preferably at least 5.0%wt, more preferably at least 5.5% wt, even more preferably at least 6.0%wt, yet more preferably at least 7.0% wt, preferably at least 8.0% wt,more preferably at least 9.0% wt, even more preferably at least 10.0%wt, yet more preferably at least 11.0% wt, preferably at least 12.0% wt,more preferably at least 13.0% wt, even more preferably at least 14.0%wt, yet more preferably at least 15.0% wt of lead.

Lead is also a valuable metal. In addition, the presence of leadfacilitates the recovery of the even higher valuable tin metal, becauseit behaves similarly like tin, ends up in the same process streams,forming a mixture called “solder”, and the resulting solder streams havea higher density and are therefore easier to separate from lower densityliquid streams such as slag or solid streams such as dross. Theapplicants therefore prefer to have a significant amount of lead intheir process. In addition, the applicants prefer to recover this leadfrom raw materials of low economic value, in which lead is typicallypresent in low concentrations. Such low value raw materials oftencontain high amounts of elements that are difficult to process in apyrometallurgical copper refining process, and therefore are usuallyfirst processed in a smelter step. The lead in those low value rawmaterials therefore mainly ends up as part of the black coppercomposition. The applicants prefer to obtain as much lead as possiblefrom such low value raw materials, and hence prefer to have the blackcopper composition of the process according to the present inventioncontain as much lead as possible within the other process constraints.

A higher presence of tin and/or lead in the black copper brings theadvantage that the raw materials containing this tin and/or lead may beprocessed in a smelter step, a step which is highly tolerant for otherimpurities, much higher than this of the typical steps performed as partof a copper refining process, including any steps associated withco-production of other non-ferrous metals such as tin and/or lead. Theseacceptable raw materials thus typically are of much lower quality andhence also lower economic value. Most of the tin and/or lead in theblack copper of the process according to the present invention ends upin a crude solder co-product, which is a product of relatively higheconomic value. The economic upgrade of the tin and/or lead in the blackcopper fed to the process according to the present invention istherefore typically much higher than a same amount introduced as part ofa much more concentrated raw material that may be acceptable directly inone of the steps in the copper refining process, including ancillaries.

The applicants therefore prefer to have higher amounts of tin and/orlead in the black copper, because it brings the advantage that within alimited amount of these metals to be produced because of equipmentlimitations, more of these metals are being recovered from low value rawmaterials, and hence more of these metals may be recovered with a higheconomic upgrade from their lower value in the raw material and theirhigh economic value in the final product.

In an embodiment of the process according to the present invention, theblack copper comprises at most 15.0% wt of tin, preferably at most 14.0%wt, more preferably at most 13.0% wt, even more preferably at most 12.0%wt, yet more preferably at most 11.0% wt, preferably at most 10.0% wt,more preferably at most 9.0% wt, even more preferably at most 8.0% wt,yet more preferably at most 7.0% wt, preferably at most 6.0% wt of tin.The applicants have found that limiting the tin concentration in theblack copper composition to the specified upper limits brings theadvantage that sufficient room is left in the black copper compositionfor other metals and elements. As argued above, copper presence ishighly advantageous in the upstream smelter step, and so is the presenceof lead. The applicants therefore prefer to keep the concentration oftin within the specified upper limit.

In an embodiment of the process according to the present invention, theblack copper comprises at most 25.0% wt of lead, preferably at most24.0% wt, more preferably at most 23.0% wt, even more preferably at most22.0% wt, yet more preferably at most 21.0% wt, preferably at most 20.0%wt, more preferably at most 19.0% wt, even more preferably at most 18.0%wt, yet more preferably at most 17.0% wt, preferably at most 16.0% wt,more preferably at most 15.0% wt, yet more preferably at most 14.0% wt,even more preferably at most 13.0% wt, yet more preferably at most 12.0%wt, preferably at most 11.0% wt, more preferably at most 10.0% wt, evenmore preferably at most 9.0% wt, yet more preferably at most 8.0% wt,preferably at most 7.0% wt of lead. The applicants have found thatlimiting the lead concentration in the black copper composition to thespecified upper limits brings the advantage that sufficient room is leftin the black copper composition for other metals and elements. As arguedabove, copper presence is highly advantageous in the upstream smelterstep, and also the presence of significant amounts of tin is highlydesirable. The applicants, therefore, prefer to keep the concentrationof lead within the specified upper limit.

The applicants have found that excessive amounts of tin and/or lead inthe black copper affect any separation step between copper (and nickel)on the one hand and of tin and lead on the other hand. The separation isless clear, and more tin and/or lead tends to stay with the copper. Evenif the copper stream is at least partially recycled, this causes higheramounts of tin and/or lead to circulate around in the process and takingup furnace volume. But also if the copper stream from that separation,or part thereof, is removed from the process, the higher amounts of tinand/or lead in that stream represent an extra burden for its downstreamprocessing.

In an embodiment of the process according to the present invention, theblack copper comprises at least 0.1% wt and optionally at most 4.0% wtof nickel (Ni). Preferably the black copper feed to step b) comprises atleast 0.2% wt of nickel, more preferably at least 0.3% wt, even morepreferably at least 0.4% wt, yet more preferably at least 0.5% wt,preferably at least 0.75% wt, more preferably at least 1.00% wt ofnickel.

Nickel is a metal that is present in many raw materials containingcopper, tin and/or lead, and it is also present in many alloyscontaining or even based on iron. Nickel exhibits under the furnaceconditions an affinity for oxygen that is lower than tin and/or lead,close to and somewhat higher than this of copper. It is therefore ametal that is difficult to separate from copper by pyrometallurgy. InU.S. Pat. No. 3,682,623, most of the nickel comprised in the pre-refinedblack copper (Table VI, 541.8 kg) leaves the process as an impurity inthe refined copper product (Table XII, 300 kg), which was cast intoanodes (col. 19, lines 61-62). A minor amount of the nickel finds itsway into the lead/tin metal product (Table XV, 110 kg). The processcomprises a significant recycle stream of black copper, in which nickelappears to increase with each cycle (Table XIV, 630 kg compared to TableVI, 500 kg). The applicants have found that nickel in the copper anodesis a disturbing element in the downstream electrorefining step. Underthe electrorefining process conditions, the nickel dissolves in theelectrolyte but does not deposit on the cathode. It therefore may buildup in the electrolyte and may possibly lead to nickel saltsprecipitating when exceeding their solubility limit. But even at lowerlevels, the nickel may already lead to anode passivation because of apossible build-up of a nickel concentration gradient at the anodesurface. The process of U.S. Pat. No. 3,682,623 is thus limited in itsnickel handling capabilities. The melting step in U.S. Pat. No.3,682,623 may therefore only accept a rather limited amount of rawmaterials that contain significant amounts of nickel.

The applicants have now found that the process according to the presentinvention is able to accept much higher amounts of nickel, e.g. as partof the black copper from an upstream smelter step. This higher tolerancefor nickel brings for the process according to the present invention,and for any process steps performed upstream, a wider window ofacceptance with respect to raw materials. The process according to thepresent invention, as well as any of its upstream process steps, maythus accept raw materials that alternate processes known in the art maynot accept, or only accept in very limited quantities, and which maythus be more readily available at economically more attractiveconditions.

In spite of the higher tolerance for nickel, we have also found that theprocess according to the present invention may be capable of producing aprime anode copper product that is richer in copper and comprises lessnickel as compared to the anode copper produced in U.S. Pat. No.3,682,623.

In an embodiment of the process according to the present invention, theblack copper comprises at most 3.5% wt of iron, preferably at most 3.0%wt, more preferably at most 2.5% wt, even more preferably at most 2.0%wt, yet more preferably at most 1.80% wt, preferably at most 1.60% wt ofiron.

In an embodiment of the process according to the present invention, theblack copper comprises at most 8.0% wt of zinc, preferably at most 7.5%wt, more preferably at most 7.0% wt, even more preferably at most 6.5%wt, yet more preferably at most 6.0% wt, preferably at most 5.5% wt,more preferably at most 5.0% wt, even more preferably at most 4.7% wt ofzinc.

The applicants have found that it is advisable to keep theconcentrations of iron and/or zinc within the specified boundaries.These metals are typically oxidized in the copper refining steps, wherethey consume ancillaries. Zinc is readily reduced in any of the reducingsteps of the process, and hence also there consumes ancillaries. Inaddition, these metals take up furnace volume. For these reasons, theapplicants want to limit these metals to the respective concentrationsas specified.

In an embodiment of the process according to the present invention, thetemperature of the slag in step b) and/or in step c) is at least 1000°C., preferably at least 1020° C., more preferably at least 1040° C.,even more preferably at least 1060° C., preferably at least 1080° C.,more preferably at least 1100° C., even more preferably at least 1110°C., preferably at least 1120° C., more preferably at least 1130° C.,even more preferably at least 1140° C., preferably at least 1150° C. Theapplicants have found that the separation between the metal phase andthe slag phase is better when the temperature of the slag is incompliance with the prescribed limit, and preferably above theprescribed limit. Without wanting to be bound by this theory, theapplicants believe that the higher temperature brings a betterseparation at least because the viscosity of the slag is lower at highertemperatures. A lower slag viscosity allows the heavier metal bubbles tocombine faster into larger bubbles and to sink faster through the slagphase until they reach the underlying metal phase and may combinetherewith. A higher temperature also brings the advantage of fasterreaction kinetics, such that a desired equilibrium may be reachedfaster.

The applicants however also believe that the equilibrium between metaland slag phase is affected by the temperature. Usually a highertemperature tends to decrease the differences between different metalsin terms of their affinity for oxygen under the process conditions. Theapplicants therefore prefer to limit the furnace temperature in step b)and/or c) to at most 1300° C., preferably at most 1250° C., morepreferably at most 1200° C. The applicants prefer to apply this limit tomost, if not all of the steps in the process according to the presentinvention in which there is made a phase separation between at least twoliquid phases, usually a supernatant slag phase and an underlying metalphase.

At the high temperatures in a non-ferrous metal smelting or refiningstep, the metals and the metal oxides are both occurring in a liquidmolten state. The metal oxides usually have a lower density than themetals and form a separate so-called “slag” phase which comes floatingas a supernatant liquid phase on top of the molten metal phase. Themetal oxides may thus be separated by gravity as a separate liquid slagphase from the molten metal phase. Silica, usually in the form of normalsand, may be added as a so-called “flux material”, i.e. as a slagdiluent and/or for improving the slag fluidity such that it separatesmore readily from the metal phase and it is easier to handle. The silicais also capable of binding particular elements, and thereby also affectsthe desire of that element to become part of the slag phase rather thanthe metal phase. The applicants have found that the addition of silicais a highly desirable process element for many of the steps that arepart of the process according to the present invention where a slagphase and a metal phase are to be separated from each other, because thesilica in many circumstances assists in changing the equilibrium betweenthe metal phase and the slag phase in the favour of the separation thatis desired with respect to the metals desired in the metal phase and themetals preferred to stay in the slag phase. The applicants have furtherfound that when the slag contains iron and is withdrawn from the furnaceand granulated by contacting the hot liquid slag with water, theaddition of silica may avoid the risk that the iron is present in a formwhich acts as a catalyst for the splitting of water and hence theformation of hydrogen gas, which represents an explosion hazard. Silicaalso increases the activity of any tin in the slag, forcing some SnO₂ toreduce to Sn metal, which Sn will move to the metal phase. This lastmechanism reduces the amount of Sn that remains in the slag for the sameunderlying metal composition.

At the operating conditions of pyrometallurgy, several chemicalreactions take place between the various metals and oxides in thefurnace. The metals having a higher affinity for oxygen are more readilyoxidized and those oxides tend to move into the slag phase, while themetals having a lower affinity for oxygen, when present as oxides,readily reduce to return to their metal state and these metals tend tomove into the liquid metal phase. If sufficient contacting surface andtime is allowed, an equilibrium establishes between the metal phase, inwhich the metals having a lower affinity for oxygen under the processconditions collect, and the slag phase, in which the metals having ahigher affinity for oxygen under the process conditions are collectingin the form of their oxides.

Metals such as sodium (Na), potassium (K), calcium (Ca) and silicon (Si)have an extremely high affinity for oxygen and will almost exclusivelybe retrieved in the slag phase. Metals such as silver (Ag), gold (Au)and other precious metals have an extremely low affinity for oxygen, andare almost exclusively retrieved in the metal phase. Most other metalstypically behave “in-between” these two extremes, and their preferencemay in addition be affected by the presence of other elements orsubstances, or maybe the relative absence thereof.

The metals of interest for this invention have, under the typicalfurnace conditions of non-ferrous metal refining, affinities for oxygen,and will tend to distribute between the metal and the slag phase. Fromlower to higher affinity for oxygen, and hence from a relatively highaffinity to a lower affinity for the metal phase, the ranking of thesemetals may be represented roughly as follows:Au>Ag>>Bi/Cu>Ni>As >Sb>Pb>Sn>>Fe>Zn>Si>Al>Mg>Ca. For convenience, onemay call this a ranking of the metals from the more noble to the lessnoble, but this qualification has to be linked to the particularconditions and circumstances of non-ferrous metal pyrometallurgicalprocesses, and may fail when exported into other fields. The relativeposition of particular metals in this list may a.o. be affected by thepresence or absence of other elements in the furnace, such as e.g.silicon.

The equilibrium distribution of metal between metal and slag phase mayalso be influenced by adding oxygen and/or oxygen scavenging materials(or reducing agents) into the liquid bath in the furnace.

Oxygen addition will convert some of the metals in the metal phase intotheir oxidised form, which oxide will then move into the slag phase. Themetals in the metal phase which have a high affinity for oxygen will bemore prone for undergoing this conversion and move. Their equilibriumdistribution between metal and slag phase may thus be more subject tochange.

The opposite may be obtained by adding oxygen scavenging materials.Suitable oxygen consumers may for instance be carbon and/or hydrogen, inwhatever shape or form, such as in organic materials, e.g. wood, orother combustibles, such as natural gas. Carbon and hydrogen willreadily oxidize (“burn”) and convert to H₂O and/or CO/CO₂, componentsthat readily leave the liquid bath and entrain its oxygen content fromthe bath. But also metals such as Si, Fe, Al, Zn and/or Ca are suitablereducing agents. Of particular interest are iron (Fe) and/or aluminium(Al), because of their ready availability. By oxidizing, thesecomponents will reduce some of the metals in the slag phase from theiroxidized state into their metal state, and these metals will then moveinto the metal phase. Now it are the metals in the slag phase which havea lower affinity for oxygen that will be more prone for undergoing thisreduction reaction and for making the move in the opposite direction.

In a smelter step, one of the purposes is to reduce oxides of valuablenon-ferrous metals that are coming in with the feed into theircorresponding reduced metals. The direction and speed of the reactionsoccurring in the smelter step may additionally be steered by controllingthe nature of the atmosphere in the furnace. Alternatively or inaddition, oxygen donating material or oxygen scavenging material may beadded to the smelter.

A highly suitable oxygen scavenging material for such operations is ironmetal, usually scrap iron being preferred. Under the typical operatingconditions, the iron will react with hot oxides, silicates and the othercompounds of metals having a lower affinity for oxygen than iron, toyield a melt containing the latter metals in elemental form. Typicalreactions include:

MeO+Fe→FeO+Me+heat

(MeO)_(x)SiO₂ +xFe→(FeO)_(x)SiO₂ +xMe+heat

The temperature of the bath remains high through the exothermic heat ofreaction and the heat of combustion. The temperature may readily be keptwithin a range in which the slag remains liquid and volatilization oflead and/or tin remains limited.

Each of the reduction reactions taking place in the melting furnace forman equilibrium. Thus, the conversion realized through each reaction islimited by the equilibria defined in relationships such as thefollowing:

${K\; 1} = \frac{\left. {FeO} \right\rbrack\mspace{11mu}\lbrack{Me}\rbrack}{\lbrack{MeO}\rbrack\mspace{11mu}\lbrack{Fe}\rbrack}$${K\; 2} = \frac{{\left\lbrack {({FeO})_{x}{SiO}_{2}} \right\rbrack\mspace{11mu}\lbrack{Me}\rbrack}^{x}}{{\left\lbrack {({MeO})_{x}{SiO}_{2}} \right\rbrack\mspace{11mu}\lbrack{Fe}\rbrack}^{x}}$

The parameters in these formulae are representing the activities of thementioned chemical components under the operating conditions, oftenbeing the multiplication of the concentration of the component times theactivity coefficient of the component under the operating conditions,whereby the latter is not always equal to 1.0 or the same for differentcomponents. The applicants have found that the activity coefficients maybe influenced by the presence of other chemical compounds, such asso-called flux compounds, sometimes also called slag formers, inparticular by the addition of silicon dioxide.

In the case where Me is copper, K1 and K2 are high at normal reactiontemperatures and reduction of copper compounds thus proceedssubstantially to completion. In the case of lead and tin, K1 and K2 areboth relatively low, but the copper in the metal phase extracts metalliclead and tin from the slag reaction zone, thereby lowering theactivities of these metals in the slag and driving the reduction ofcombined lead and tin to completion.

The vapour pressure of zinc is relatively high at the typical reactiontemperature and a major proportion of zinc, in contrast to lead and tin,may readily be volatilized out of the furnace. Zinc vapours leaving thefurnace are oxidized by air which may e.g. be aspirated between thefurnace mouth and the hood and/or the exhaust pipe. The resultant zincoxide dust is condensed and collected by means of conventional dustcollecting systems.

Preferably, the copper, tin and lead content of the slag in the smelterfurnace are each reduced to 0.5% wt or less. For that purpose, the metalphase should contain sufficient copper to act as the solvent forextracting the lead and tin present from the slag. Also for this reason,the applicants prefer the copper concentration in the black copper fedto the process according to the present invention to be above the lowerlimit specified elsewhere in this document.

In an embodiment, the process according to the present invention furthercomprises the step of

-   h) partially oxidizing the first enriched copper metal phase,    thereby forming a second enriched copper metal phase and a second    copper refining slag, followed by separating the second copper    refining slag from the second enriched copper metal phase.

The applicants have found that the first enriched copper metal phaseformed in step b) may be further enriched in copper by submitting thestream to a subsequent oxidation step. The subsequent oxidation stepleads to the formation of a second copper refining slag which maycontain economically significant amounts of valuable metals other thancopper, but in which also an economically significant amount of copperis entrained.

In an embodiment of the process according to the present inventionincluding step h), at least 37.0% wt of the total amount of the tin andlead that is processed through process steps b) and/or h) is retrievedin the first copper refining slag and the second copper refining slagtogether.

In an embodiment of the process according to the present inventionincluding step h), at least 37.5% wt and better at least 38% wt of thetotal amount of the tin and lead that is processed through process stepsb) and/or h) is retrieved in the first copper refining slag and thesecond copper refining slag together, preferably at least 40% wt, morepreferably at least 45% wt, even more preferably at least 50% wt,preferably at least 60% wt, more preferably at least 70% wt, even morepreferably at least 80% wt, yet more preferably at least 85% wt,preferably at least 90% wt, more preferably at least 92% wt, even morepreferably at least 94% wt, yet more preferably at least 95% wt of thetotal amount of the tin and lead that is processed through process stepsb) and/or h). The applicants have found that a high recovery of the tinand/or lead into the early slags of the copper refining step sequence isadvantageous for obtaining a better separation between the copper on theone hand and the solder metals tin and/or lead on the other hand.

In an embodiment of the process according to the present invention, atleast 8.5% wt of the total amount of the tin and lead that is processedthrough process step b) is retrieved in the first copper refining slag,preferably at least 10% wt, more preferably at least 15% wt, even morepreferably at least 20% wt, preferably at least 30% wt, more preferablyat least 40% wt, even more preferably at least 45% wt, yet morepreferably at least 50% wt, preferably at least 55% wt, more preferablyat least 60% wt, even more preferably at least 64% wt, yet morepreferably at least 68% wt of the total amount of the tin and lead thatis processed through process step b). The applicants have found that theearlier in the sequence of the copper refining steps b) and h) that moreof the tin and/or lead is oxidized and moved into the copper refiningslag phase, the clearer the overall separation between the copper on theone hand and the solder metals on the other hand can be made.

In an embodiment of the process according to the present inventionincluding step h), at least 41.0% wt of the total amount of the tin thatis processed through process steps b) and/or h) is retrieved in thefirst copper refining slag and the second copper refining slag together,preferably at least 45% wt, more preferably at least 50% wt, even morepreferably at least 55% wt, preferably at least 60% wt, more preferablyat least 65% wt, even more preferably at least 70% wt, preferably atleast 75% wt, more preferably at least 80% wt, yet more preferably atleast 85% wt, preferably at least 90% wt, more preferably at least 92%wt of the total amount of the tin that is processed through processsteps b) and/or h).

In an embodiment of the process according to the present inventionincluding step h), at least 34.5% wt of the total amount of the leadthat is processed through process steps b) and/or h) is retrieved in thefirst copper refining slag and the second copper refining slag together,preferably at least 35% wt, more preferably at least 40% wt, even morepreferably at least 45% wt, preferably at least 50% wt, more preferablyat least 55% wt, even more preferably at least 60% wt, yet morepreferably at least 65% wt, preferably at least 70% wt, more preferablyat least 75% wt, even more preferably at least 80% wt, preferably atleast 85% wt, more preferably at least 90% wt, even more preferably atleast 91% wt of the total amount of the lead that is processed throughprocess steps b) and/or h)

In an embodiment, the process according to the present invention furthercomprises the step of

-   i) adding at least a part of the second copper refining slag to the    first liquid bath and/or adding at least a part of the second copper    refining slag to step d).

The applicants have found that the composition of the second copperrefining slag is highly suitable for being added into the first liquidbath. The applicants therefore prefer to add all of the second copperrefining slag into the first liquid bath. The stream is suitable in thefirst place because the second copper refining slag is alreadyrelatively rich in the valuable metals of interest tin and lead, butalso includes significant amounts of copper which may act downstream asan extracting agent for non-copper metals such as tin and lead. In thesecond place, the second copper refining slag contains only low amountsof metals having under the process conditions a higher affinity foroxygen than tin and/or lead, more particularly metals that are lessdesired in the final purified metal products copper, tin and/or lead,and which metals will have to be removed from the process as part of aspent slag. Because the second copper refining slag is relatively poorin such metals, the addition of this slag into the first liquid bathdoes not consume high useless furnace volume in any of the downstreamsteps in the process sequence d), e) and f), i.e. the preferred processpath for such “less noble” metals for ending up in a spent slag, in thiscase the second spent slag.

The applicants have found that the process according to the presentinvention including steps b), h), c), i) and d) is highly effective forthe production of a slag phase, i.e. the first solder refining slag, aslag which is particularly suitable for producing a derivative solderstream, i.e. the first crude solder metal composition, which may serveas an intermediate for the recovery of high purity tin and/or leadproducts. The applicants have found that this effectiveness isparticularly due to the obtaining, in step d), of the first dilutecopper metal composition, but also because of the sequence of oxidationand reduction steps as specified.

The applicants have further found that the process including steps i)and d) is also highly energy efficient. In step d), the second copperrefining slag which may be added in step i) acts as an oxidant forimpurities in the first liquid bath. The copper oxides in the secondcopper refining slag readily reduce to elemental copper, releasing theoxygen and making that oxygen available for converting those metalswhich are having under the process conditions a higher affinity foroxygen than copper, from their elemental metal form into oxides. Theelemental copper formed in step d) therefore moves to the metal phaseand leaves step d) with the first dilute copper metal composition. Themetals that convert to their oxides in step d) will move to the slagphase and be retrieved in the first solder refining slag. The applicantshave found that in step d) a significant amount of Sn and/or Pb may bemoved from the metal phase that is entered into the furnace towards thefirst solder refining slag that is present at the end of step d). Theapplicants have also found that these chemical conversions in step d),of copper oxides to elemental copper and of tin, lead or other metalsinto their oxides, may be achieved with relatively little extra input ofenergy, external oxidants and/or reductants, and hence with very littleconsumption of process chemicals.

The applicants have also found that it is advantageous that step c)takes only the first copper refining slag, and that any subsequentcopper refining slags are better processed separately and preferablyeach in a different manner. The applicants have found that the firstcopper refining slag is the copper refining slag containing the highesttotal amount of elements other than copper, and particularly theelements having under furnace conditions a higher affinity for oxygenthan copper, more particularly an affinity for oxygen that is higherthan also tin and lead. The applicants have therefore surprisingly foundthat it is most effective to perform step c) on the first copperrefining slag, i.e. before mixing in any of the other copper refiningslags that are produced in process steps downstream of step b). Theapplicants have found that subsequent copper refining slags typicallycomprise higher concentrations of copper, and therefore the applicantsprefer to process these downstream copper refining slags differentlyfrom the first copper refining slag.

In an embodiment, the process according to the present invention furthercomprises the steps of

-   j) partially oxidizing the second enriched copper metal phase,    thereby forming a third enriched copper metal phase and a third    copper refining slag, followed by separating the third copper    refining slag from the third enriched copper metal phase,-   k) adding at least a part of the third copper refining slag to the    first dilute copper metal composition, thereby forming a second    liquid bath and/or adding at least a part of the third copper    refining slag to step l);-   l) partially oxidizing the second liquid bath, thereby forming a    first high-copper metal composition and a third solder refining    slag, followed by separating the third solder refining slag from the    first high-copper metal composition.

The applicants have found that the second enriched copper metal phaseformed in step h) may be further enriched in copper by submitting thestream to the subsequent oxidation step j). The subsequent oxidationstep leads to the formation of the third copper refining slag, which maystill contain economically significant amounts of valuable metals otherthan copper, but in which also an economically significant amount ofcopper is entrained. The advantage is that these valuable non-coppermetals become recoverable from the third copper refining slag in a muchmore simple manner as compared to the amounts of non-copper metalsremaining in the third enriched copper metal phase if this stream wouldbe subjected to a copper electrorefining step for the recovery of highpurity copper in which the non-copper metals have a tendency torepresent a process burden. Some non-copper metals remain duringelectrorefining in the so-called anode slime and some other non-coppermetals dissolve in the electrolyte.

The applicants have further found that the three consecutive oxidationsteps as part of the series b), h) and j) are able to produce, from ablack copper starting raw material which may be rather dilute in copperbut rich in tin and/or lead, a third enriched copper metal phase whichhas a copper concentration which is highly suitable for furtherpurification by electrorefining, hence may be called “anode grade”. Theapplicants have found that the sequence of oxidation steps as specifiedis able, from a black copper of hardly more than 75% wt of copper toproduce a third enriched copper metal phase which contains as much as99.0% wt of copper. The applicants have further found that, togetherwith processing of the black copper fed to step b), extracopper-containing raw materials may be processed through the specifiedsequence of oxidation steps.

The applicants have found that the composition of the third copperrefining slag is highly suitable for being added into the second liquidbath. The applicants therefore prefer to add all of the third copperrefining slag into the second liquid bath.

The stream is firstly suitable because the third copper refining slagstill contains economically significant amounts of the valuable metalsof interest tin and/or lead, but is also relatively rich in copper,which may be used as a useful extracting agent for non-copper metalssuch as tin and/or lead.

In the second place, the third copper refining slag contains very littleamounts of metals having under the process conditions a higher affinityfor oxygen than tin and/or lead, more particularly metals that are lessdesired in the final purified metal products copper, tin and/or lead,and which metals are preferably removed from the process according tothe present invention as part of a spent slag. Because the third copperrefining slag is very poor in such metals, the addition of this slaginto the second liquid bath causes very little useless furnace volume tobe consumed unnecessarily in any of the downstream steps in the process,including step l) but also in any of the downstream steps in the processpath that such “less noble” metals need to follow before they areeventually ending up in a spent slag.

The applicants have further found that any further recovery of valuablemetals from the second liquid bath, such as in step l), may be highlyenergy efficient because of the addition of at least a part of the thirdcopper refining slag in step k). In step k), the third copper refiningslag which is added into the second liquid bath upstream of any furthermetal recovery steps acts as an oxidant for impurities in the secondliquid bath. The copper oxides in the third copper refining slag readilyreduce to elemental copper in step l), thereby releasing the oxygen forconverting metals having under the process conditions a higher affinityfor oxygen than copper from their elemental metal form into oxides. Theelemental copper formed in the processing of the second liquid bath instep l) therefore moves to the metal phase, in step l) being the firsthigh-copper metal composition. The metals that convert to their oxidesin step l) move to the slag phase, i.e. the third solder refining slag.The applicants have found that in step l) a significant amount of Snand/or Pb may be moved from the metal phase being fed, towards the slagphase. The applicants have also found that these chemical conversions instep l), of copper oxides to elemental copper and of tin, lead and/orother metals into their oxides, may be achieved with relatively limitedextra input of energy, external oxidants and/or reductants, and hencewith relatively limited consumption of energy or input of processchemicals.

The applicants have found that in step l), most of the copper and nickelpresent in the first dilute copper metal composition as well as in thethird copper refining slag may be recovered in the first high-coppermetal composition, together with some of the bismuth and antimony thatmay be present, while most of the tin and/or lead in those streams maybe recovered in the third solder refining slag. The applicants havefound that the third solder refining slag may become advantageously richin tin and/or lead and also relatively lean in copper, such that thisslag may be relatively easily further processed for recovery of most ofits solder metals into a stream that resembles a crude solder stream andis suitable for being processed as a crude solder stream.

In an embodiment of the process according to the present inventionincluding steps b), h), c), d), j) and l) the first high-copper metalcomposition is at least partially recycled to a suitable locationupstream in the process. Preferably this location is step b), but aportion of the recycled stream may be recycled to step h) and/or step j)and/or step c) and/or step d).

The applicants have found that on the one hand the step l) is alsohighly suitable for providing a path for the removal of at least a partof the nickel from the overall foundry process, because any nickel beingintroduced at any upstream location into the process is likely to end upas part of the first high-copper metal composition. The applicants havefound on the other hand, that if no or only a low amount of nickel isintroduced with the feeds into the overall process, that the firsthigh-copper metal composition has a composition which is highlycomparable to the black copper feed provided in step a), that thereforethis first high-copper metal composition stream may readily be recycledto step b), or alternatively and/or in addition partially to any one ofthe subsequent copper oxidation steps h) and j), for the recovery of itscopper as part of the third enriched copper metal phase. The processdescribed in U.S. Pat. No. 3,682,623 includes such a recycle of acopper-rich stream to the first oxidation step performed on the blackcopper. Any recycle of the first high-copper metal composition to thestep b), or to one of the subsequent steps h) or j) however benefits incomparison to the prior art from the upstream removal of impurities intoone of the spent slags, such as the first spent slag produced in step c)and/or the second spent slag produced in step f).

The applicants have found, if nickel is present in the feeds to theprocess, that a partial recycle of the first high-copper metalcomposition to an upstream location in the process, such as step b), h)or j), brings the advantage that nickel concentrates up to a higherlevel in the first high-copper metal composition, as compared to aprocess without such partial recycle. This concentration effect bringsthe advantage that the withdrawal of a particular amount of nickel fromthe process, e.g. in order to keep the levels of nickel in particularsteps of the process below particular levels, requires a lower amount ofcopper to be withdrawn together with the amount of nickel. This bringsthe advantages that the removal of nickel from the process is moreeffective, that the further processing of the withdrawn copper/nickelmixture may be operated more effectively and in smaller equipment, andmay also be operated more efficiently, i.e. with a lower consumption ofenergy and/or process chemicals.

The applicants have found that the first high-copper metal compositionwhich is withdrawn from the process may be further processed for therecovery of copper and nickel contained therein by means that are knownin the art, or by preference by the means described in the patentapplication with attorney docket reference PAT2529702EP00.

In an embodiment of the process according to the present inventionincluding step l), at the end of step l) the first high-copper metalcomposition is only partially removed from the furnace, and a portion ofthis metal composition is kept in the furnace together with the thirdsolder refining slag. This portion may represent at least 3% wt, 4% wtor 5% wt of the total of first high-copper metal composition present inthe furnace at the end of step l), preferably at least 10% wt, morepreferably at least 20% wt, even more preferably at least 30% wt, yetmore preferably at least 40% wt of the total of first high-copper metalcomposition present in the furnace. The applicants have found that thisamount of metal improves the operability of the furnace during thepresent and at least one of the subsequent process steps.

In an embodiment, the process according to the present invention furthercomprises the step of

-   m) partially reducing the third solder refining slag, thereby    forming a second dilute copper metal composition and a fourth solder    refining slag, followed by separating the fourth solder refining    slag from the second dilute copper metal composition.

The applicants have found that the third solder refining slag maycontain amounts of copper and/or nickel that are still rather high forderiving a crude solder type stream from this slag. The applicantstherefore prefer to include the additional partial reduction step m) aspart of the process according to the present invention. The applicantshave found that a significant amount of the copper and/or nickel presentin the third solder refining slag may readily be removed as part of thesecond dilute copper metal composition formed in step m), while most ofthe tin and/or lead may be kept as part of the fourth solder refiningslag, before subjecting the fourth solder refining slag to furtherprocessing. Preferably the step m) is operated such that at least 50% wtof the copper present in step m) is removed as part of the second dilutecopper metal composition, more preferably at least 70% wt, even morepreferably at least 80% wt, yet more preferably at least 90% wt.Alternatively or in addition, step m) is preferably operated such thatat least 50% wt of the tin present in step m) is retrieved in the fourthsolder refining slag, more preferably at least 70% wt, even morepreferably at least 80% wt, yet more preferably at least 90% wt.

In an embodiment of the process according to the present inventionincluding step m), at the end of step m) the second dilute copper metalcomposition is only partially removed from the furnace, and a portion ofthis metal composition is kept in the furnace together with the fourthsolder refining slag. This portion may represent at least 1% wt, 2% wt,3% wt, 4% wt or 5% wt of the total of second dilute copper metalcomposition present in the furnace at the end of step m), preferably atleast 10% wt, more preferably at least 20% wt, even more preferably atleast 30% wt, yet more preferably at least 40% wt of the total of seconddilute copper metal composition present in the furnace. The applicantshave found that this amount of metal improves the operability of thefurnace during at least one of the subsequent process steps.

In an embodiment, the process according to the present invention furthercomprises the step of

-   n) partially reducing the fourth solder refining slag, thereby    forming a second crude solder metal composition and a fifth solder    refining slag, followed by separating the second crude solder metal    composition from the fifth solder refining slag.

The applicants have found that the fourth solder refining slag is ahighly suitable feedstock for recovering a crude solder type material,highly acceptable for further processing into higher purity tin and/orlead prime products. The applicants have found that in the partialreduction step n), a high portion of the tin and/or lead present in thefurnace may be recovered in the second crude solder metal composition,together with practically all of the copper and/or nickel present, whilemost of the metals having under the process conditions a higher affinityfor oxygen, such as iron, may be retained as part of the fifth solderrefining slag. The applicants have found that the second crude soldermetal composition is suitable for being further processed, such as bysubjecting the stream to a treatment with silicon metal as described inDE 102012005401 A1. Alternatively or in addition, this crude solderstream, optionally post an enrichment step for increasing the tin and/orlead content, may be further tuned as described in WO 2018/060202 A1 orsimilar, and subsequently be subjected to a distillation and recovery ofthe tin and/or lead as high purity metal products, as described in thatsame document.

In an embodiment, the process according to the present invention furthercomprises the step of

-   o) partially reducing the fifth solder refining slag, thereby    forming a third lead-tin based metal composition and a third spent    slag, followed by separating the third spent slag from the third    lead-tin based metal composition.

The applicants have found that it is advantageous to provide the extrareduction step o) downstream of the crude solder production step n), inparticular a partial reduction step on the fifth solder refining slagwhich was recovered from that step n). The applicants have found thatmore valuable metals may be extracted from this fifth solder refiningslag by step o), making the remaining slag even more suitable for use ina valuable end-use application, and/or for disposing of this slag asspent slag. The applicants have further found that the extra reductionstep o) is also able to reduce leachable metals, such as lead, in theslag to sufficiently low levels such that the slag left over from stepo) may be used further as valuable material, or be discardedresponsibly, and this with a very limited number of extra treatmentsteps, and possibly without any further treatment steps, for reducingthe concentration of sensitive metals such as lead and/or zinc.

In an embodiment, the process according to the present invention furthercomprises the step of

-   p) partially oxidizing the third lead-tin based metal composition,    thereby forming a fourth lead-tin based metal composition and a    sixth solder refining slag, followed by separating the sixth solder    refining slag from the fourth lead-tin based metal composition.

The applicants have found that step p) brings the advantage that thethird lead-tin based metal composition recovered from step o) is splitinto on the one hand a metal stream in which the copper from step p)concentrates, together with most of the nickel present, and on the otherhand a slag phase in which very little copper but a significant portionof the tin and/or lead present in step p) concentrate, together withmost of the iron, and also zinc if present. The applicants have foundthat this split brings the advantage that the two streams resulting fromstep p) may be processed differently and/or separately, using steps thatare more appropriately suitable for their compositions.

In an embodiment, the process according to the present invention furthercomprises the step of

-   q) recycling at least a part of the sixth solder refining slag to    step d), preferably before oxidizing the first liquid bath, and/or    adding at least a part of the sixth solder refining slag to the    first liquid bath, and/or recycling at least a part of the sixth    solder refining slag to step e), preferably before reducing the    first solder refining slag.

The applicants prefer to recycle the sixth solder refining slag to stepd) and/or to step e) because this allows a recovery of the tin and/orlead in this slag stream into the first crude solder metal compositionfrom step e) or the second crude solder metal composition from step n),while the iron present in the sixth solder refining slag quite readilyfinds its way into the second spent slag from step f) without creatingthe risk that the iron would build up in a cycle as part of the processaccording to the present invention.

In an embodiment, the process according to the present invention furthercomprises the step of

-   r) recycling at least a part of the fourth lead-tin based metal    composition to step l), and/or adding at least a part of the fourth    lead-tin based metal composition to the second liquid bath,    preferably before oxidizing the second liquid bath as part of step    l).

The applicants prefer to recycle the fourth lead-tin based metalcomposition to step l) because this metal stream is highly suitable forbeing contacted, together with the first dilute copper metal compositionfrom step d), with the third copper refining slag from step j) that isadded to the second liquid bath, whereby the third copper refining slagis partially reduced and the two added metal compositions are partiallyoxidized and an equilibrium may establish in which most of the copperpresent in the furnace, together with the nickel and some of the tinand/or lead, end up as part of the first high-copper metal composition,while any rejectable metals (iron, silicon, aluminium), together with asignificant portion of the tin and/or lead present, end up as part ofthe third solder refining slag produced by step l).

In an embodiment of the process according to the present inventionincluding step o), step o) comprises adding a second copper containingfresh feed to the step o), preferably before reducing the fifth solderrefining slag.

The applicants have found that the addition of copper into reductionstep o) brings a significant advantage because the copper may act as anexcellent extracting agent for any other valuable metals that haveremained in the fifth solder refining slag remaining after step n), andthat this advantageous extraction may be performed without losingsignificant amounts of copper in the third spent slag that is producedin step o).

The applicants have further found that the copper-containing fresh feedwhich may be added into step o) may contain significant amounts of othervaluable metals, in particular of zinc, nickel, tin and/or lead. Theapplicants have found, provided sufficient copper is provided, that thelosses of particularly tin and/or lead into the third spent slag may bekept very low and therefore do not jeopardize the possible further usesor routing of this third spent slag, nor represent an economicallysignificant loss of valuable metals.

The applicants have found that a large variety of materials are suitableas copper-containing fresh feed to step o). The applicants howeverprefer that the copper-containing fresh feed to step o) comprises onlylimited amounts of, and preferably little to no, combustibles, i.e.substances that readily oxidize under the process conditions, e.g.organic materials such as plastics and/or hydrocarbons, rests of fuel oroil, etc., such that the temperature in step o) remains readilycontrollable.

In an embodiment of the process according to the present inventionincluding step o), the second copper containing fresh feed comprisesblack copper and/or spent or reject copper anode material.

The applicants have found that into step o) a significant amount ofblack copper, similar in composition to the black copper which wasprovided in step a), may be added for extracting more valuable metalsout of the fifth solder refining slag obtained from step n) withoutexcessively losing extra valuable metals into the third spent slag fromstep o). The applicants have found that the amounts of such black copperfrom an upstream smelter step that are acceptable in step o) are verysignificant, even of the order of magnitude of the amount of blackcopper provided in step a) as feed for step b). The applicants havefound that the inclusion of step o) into the process according to thepresent invention significantly increases the capability to processsmelter-type black copper, and hence to process higher amounts of thelower quality raw materials that bring valuable metals at low value andtherefore with a high value upgrade potential. The applicants have foundthat this way of operating step o) brings the extra advantage that asignificant portion of the black copper from the upstream smelter stepmay be processed without all that black copper needing to pass throughat least the first step b) of the copper refining sequence. Any metalsin the black copper feed to step o) that have under the processconditions a higher affinity for oxygen than copper are most likelyalready removed before the copper from this black copper fresh feed tostep o) may find its way into step b) and pass through the copperrefining process sequence of steps b), h) and j).

The applicants have also found that step o) is also highly suitable forintroducing spent and/or reject copper anode material. The production ofhigh quality copper typically comprises an electrolysis step, in whichcopper dissolves from an anode into the electrolyte and re-deposits on acathode. The anode is typically not fully consumed and the anode isremoved as spent copper anode material from the electrolysis bath beforethe last copper thereof has been dissolved. The applicants have foundthat step o) is highly suitable for introducing such spent copper anodematerial. Copper anodes for such copper electrolysis step are typicallycast by pouring a suitable amount of molten anode quality copper into amould and letting the copper solidify upon cooling. For a goodfunctioning of the copper electrolysis, the anodes have to comply withfairly stringent dimensional and shape requirements. Non-compliantanodes are preferably not used but represent reject copper anodematerial. The applicants have found that step o) is also highly suitablefor introducing such reject copper anode material.

The applicants prefer to introduce the spent and/or reject copper anodematerial as a solid with little to no preheat. This brings the advantagethat the melting of this material consumes at least a part of the heatof reaction generated by the chemical reactions occurring in step o).

In an embodiment of the process according to the present inventionincluding step o), step o) comprises adding a sixth reducing agent tostep o), preferably before reducing the fifth solder refining slag.

The applicants have found that the sixth reducing agent allows to drivethe result of reduction step o) towards the desired separation ofvaluable metals into the third lead-tin based metal composition andmaintaining rejectable metals into the third spent slag. The applicantshave found that the sixth reducing agent may be a gas such as methane ornatural gas, but may also be a solid or a liquid, such as carbon, ahydrocarbon, even aluminium or iron.

In an embodiment of the process according to the present inventionincluding step o), the sixth reducing agent comprises, and preferablyprimarily is, a metal having under the process conditions a higheraffinity for oxygen than tin, lead, copper and nickel, preferably ironmetal, more preferably scrap iron. The applicants prefer to use iron,preferably scrap iron as the reducing agent, because of its highavailability at economically very attractive conditions. The applicantshave found that the addition of the solid reducing agent may bring theadditional benefit that the furnace requires less additional heating inorder to maintain or reach its desired temperature. The applicants havefound that this benefit may be sufficiently large such that additionalheating by burning a fuel using air and/or oxygen may hardly be requiredin order to reach the desired temperature. The applicants have furtherfound that the step o) may further benefit from the addition of silica,as explained hereinabove.

The applicants prefer to add to step o) an amount of sixth reducingagent that is rich in copper and iron, preferably as multimetalmaterial, because this multimetal material is more readily available atmore advantageous conditions than higher purity tin, higher puritycopper or higher purity iron. Another suitable material may be electricmotors, preferably such motors after use, because of their high contentsof iron for the cores and copper for the windings. The applicants havefound that the copper and/or tin may readily be kept in the metal phaseand be kept from moving into the slag phase, while any iron into thiscopper-containing fresh feed readily moves into the slag phase as ironoxide, while it helps the chemical reduction of other metals that haveunder the process conditions a lower affinity for oxygen than iron.

In an embodiment of the process according to the present inventionincluding step n), step n) further comprises adding a fifth reducingagent to step n), preferably before reducing the fourth solder refiningslag.

The applicants have found that the fifth reducing agent allows to drivethe result of reduction step n) towards the desired separation ofvaluable metals into the second crude solder metal composition andmaintaining rejectable metals into the fifth solder refining slag. Theapplicants have found that the sixth reducing agent may be a gas such asmethane or natural gas, but may also be a solid or a liquid, such ascarbon, a hydrocarbon, even aluminium or iron.

In an embodiment of the process according to the present inventionincluding step n), the fifth reducing agent comprises, and preferablyprimarily is, a metal having under the process conditions a higheraffinity for oxygen than tin, lead, copper and nickel, preferably thefifth reducing agent comprises iron metal, more preferably scrap iron.The applicants prefer to use iron, preferably scrap iron as the reducingagent, because of its high availability at economically very attractiveconditions. The applicants have found that the addition of the solidreducing agent may bring the additional benefit that the furnacerequires less additional heating in order to maintain or reach itsdesired temperature. The applicants have found that this benefit maypossibly be sufficiently large that additional heating by burning a fuelusing air and/or oxygen may be limited or hardly be required in order toreach the desired temperature. The applicants have further found thatthe step n) may further benefit from the addition of silica, asexplained hereinabove.

Preferably the fifth reducing agent contains little copper and/ornickel, more preferably less than 1% wt of copper and nickel together.This brings the advantage that little or no extra copper and/or nickelshow up in the second crude solder metal composition, such that anyconsumption of process chemicals in a downstream step for refining thiscrude solder composition is not significantly increased.

In an embodiment of the process according to the present inventionincluding step n), a second Pb and/or Sn containing fresh feed is addedto step n), preferably before reducing the fourth solder refining slag,preferably the second Pb and/or Sn containing fresh feed comprising andpreferably primarily being dross obtained from downstream processing ofconcentrated streams of Pb and/or Sn.

The applicants have found that step n) is also a very suitable locationin the process for introducing materials that are rich in tin and/orlead, poor in copper and nickel, but which may contain metals whichunder the process conditions have a higher affinity for oxygen than tinand lead. Their addition to step n) brings the advantage that the tinand/or lead are readily recovered as part of the second crude soldermetal composition, and are withdrawn from the process, while theso-called “less noble” metals have a short and straight process pathwayinto the third spent slag produced in the downstream step o).

The applicants have found that step n) is very suitable for recoveringtin and/or lead, and optionally antimony and/or arsenic, in rawmaterials or process by-products that are rich in such metals yetrelatively low in copper and/or nickel. The applicants have found thatthe second Pb and/or Sn containing fresh feed may further contain metalshaving under the process conditions a higher affinity for oxygen thantin and/or lead, such as sodium, potassium, calcium. Such metals maye.g. be introduced as part of process chemicals used in downstream stepsfor refining a tin and/or lead rich stream such as the first crudesolder metal composition or a downstream derivative. The applicants havefound that step n) is very suitable for recovering valuable metals froma dross by-product formed in one of the refining steps performed as partof the processes disclosed in WO 2018/060202 A1 or similar. Such drossby-product streams typically entrain economically significant amounts oftin and/or lead, but also contain the other metals that may have beenintroduced as part of process chemicals.

In an embodiment, the process according to the present invention furthercomprises the step of

-   s) recycling at least a part of the second dilute copper metal    composition formed in step m) to step c), preferably before the    first copper refining slag is reduced, and/or recycling at least a    part of the second dilute copper metal composition to step d),    preferably before the first lead-tin metal composition is oxidized,    and/or adding at least a part of the second dilute copper metal    composition to the first liquid bath.

The applicants have found, regardless which recycle option is selectedfor recycling the second dilute copper metal composition, that thecopper recovered in the second dilute copper metal composition, inaddition to any nickel that may be present, readily is recovered in thefirst dilute copper metal composition that is formed in step d), andfurther downstream readily finds its way into the first high-coppermetal composition that is formed in step l), with which the copper maybe withdrawn from the process, while at the same time any tin and/orlead in the second dilute copper metal composition may readily find itsway into the first solder refining slag formed in step d) and may thenfurther downstream be recovered as part of the first crude solder metalcomposition formed in step e), with which they may be withdrawn from theprocess.

In an embodiment of the process according to the present inventionincluding step m), step m) further comprises adding a fourth reducingagent to step m) before reducing the third solder refining slag.

The applicants have found that the fourth reducing agent allows to drivethe result of reduction step m) towards the desired separation ofvaluable metals into the second dilute copper metal composition andmaintaining rejectable metals into the fourth solder refining slag. Theapplicants have found that the fourth reducing agent may be a gas suchas methane or natural gas, but may also be a solid or a liquid, such ascarbon, a hydrocarbon, even aluminium or iron.

In an embodiment of the process according to the present inventionincluding step m), the fourth reducing agent comprises, and preferablyprimarily is, a metal having under the process conditions a higheraffinity for oxygen than tin, lead, copper and nickel, preferably ironmetal, more preferably iron scrap.

The applicants prefer to use iron, preferably scrap iron as the reducingagent, because of its high availability at economically very attractiveconditions. The applicants have found that the addition of the solidreducing agent may bring the additional benefit that the furnacerequires less additional heating in order to maintain or reach itsdesired temperature. The applicants have found that this benefit may besufficiently large such that additional heating by burning a fuel usingair and/or oxygen may be limited or even hardly required in order toreach the desired temperature. The applicants have further found thatthe step m) may further benefit from the addition of silica, asexplained hereinabove.

The applicants prefer to add to step m) an amount of fourth reducingagent that is rich in copper and iron, preferably as multimetalmaterial, because this multimetal material is more readily available atmore advantageous conditions than higher purity tin, higher puritycopper or higher purity iron. Another suitable material may be electricmotors, preferably such motors after use, because of their high contentsof iron for the cores and copper for the windings. The applicants havefound that the copper may readily be kept in the metal phase and be keptfrom moving into the slag phase, while any tin, lead and iron into thiscopper-containing fresh feed readily moves into the slag phase as theirrespective oxides, while it helps the chemical reduction of other metalsthat have under the process conditions a lower affinity for oxygen thantin, lead and iron.

In an embodiment, the process according to the present invention furthercomprises the step of

-   g) recycling at least a part of the second lead-tin based metal    composition to step c), preferably adding most if not all of the    second lead-tin based metal composition to step c), and preferably    before reducing the first copper refining slag, and/or recycling at    least a part of the second lead-tin based metal composition to    step b) and/or recycling at least a part of the second lead-tin    based metal composition to step d).

The applicants have found that the valuable metals in the secondlead-tin based metal composition from step f) may readily be recoveredby adding this composition to step c), and/or step b) and/or step d).The metals in the second lead-tin based metal composition having ahigher affinity for oxygen under the process conditions, readily oxidizeand result in a reduction of those metals being fed to step c) that havea lower affinity for oxygen under the same conditions. The presence instep c) of the extra metals from step f) result in a partial reductionof the metals present as oxides in the first copper refining slag. As aresult, more valuable metals, such as Cu, Ni, Sn, Pb, Sb, As, move intothe metal phase of step c), and more rejectable metals, such as Fe, Siand Al, move into the first spent slag produced in step c). The additionof this second lead-tin based metal composition into step c) thereforeimproves the desired separation of the other feedstocks to step c) incombination with obtaining a desired separation of the metals that havebeen recovered from step f).

In an embodiment of the process according to the present invention, atleast to one of the process steps involving the separation of a metalphase from a slag phase, is added an amount of silica, preferably in theform of sand.

The applicants have found that the silica promotes the formation of theslag phase, improves the slag fluidity and improves the separation bygravity of the metal phase from the slag phase. Without wanting to bebound by this theory, the applicants believe that the reduction of theslag viscosity by itself significantly improves the phase separationbecause the metal bubbles formed in the slag phase because of a chemicalreduction more readily move through the slag phase and may thus arriveat the interphase between the two phases, where they are able to becombined with the underlying continuous metal phase. The addition ofsilica further beneficially affects the equilibrium of particular metalsbetween the metal phase and the slag phase, in particular for lead. Thesilica also increases the acidity of the slag, which further affects theequilibria in the furnace between the different phases. When the slagcontains iron and is withdrawn from the furnace and granulated bycontacting the hot liquid slag with water, the addition of silica mayavoid the risk that the iron is present in a form which acts as acatalyst for the splitting of water and hence the formation of hydrogengas, which represents an explosion hazard. Silica also increases theactivity of any tin in the slag, forcing some SnO₂ to reduce to Snmetal, which Sn will move to the metal phase. This last mechanismreduces the amount of Sn that remains in the slag for the sameunderlying metal composition.

In an embodiment of the process according to the present invention inwhich a black copper is added to at least one of steps b), f) and o),wherein the black copper is produced by a smelter step.

The applicants have found that a smelter step is highly suitable, andeven preferable, for producing any one and preferably all of the blackcopper compositions that are used as possible feed and fresh feeds tosteps of the process according to the present invention, in particularsteps b), h), f) and/or o). A smelter step offers the advantage of beingsimple in operation and in equipment, hence economically advantageous. Asmelter step brings the further advantage of being tolerant in terms ofraw material quality. A smelter step is able to accept raw materialsthat are highly diluted and/or contaminated with a wide variety ofcomponents, as described above in this document. Because these mixedand/or contaminated raw materials have hardly any other end-use, theymay be supplied at economically very attractive conditions. Thecapability of processing these raw materials and upgrading the valuablemetals contained therein, is therefore of interest to the operator ofthe process according to the present invention.

In a smelting furnace the metals are molten, and organics and othercombustible materials are burned off. Metals having a relatively highaffinity for oxygen convert to their oxides and collect in the lowerdensity supernatant slag phase. The metals having a lower affinity foroxygen remain as elemental metal and remain in the higher density liquidmetal phase on the bottom of the smelter furnace. In a copper productionstep, the smelting step may be operated such that most iron ends up inthe slag, while copper, tin and lead end up in the metal product, astream which is typically called “black copper”. Also most of thenickel, antimony, arsenic and bismuth end up as part of the black copperproduct.

The applicants have found that the metal product from a smelter step maybe introduced into the process according to the present invention as amolten liquid, but may alternatively be allowed to solidify and cooldown, such as by granulation, which allows for possible transportbetween different industrial sites, and subsequently be introduced intothe process before or after being melted again.

In an embodiment of the process according to the present invention, atleast one of the first crude solder metal composition and the secondcrude solder metal composition is pre-refined using silicon metal toproduce a pre-refined solder metal composition. A suitablepre-refinement treatment for such crude solder metal composition isdescribed in DE 102012005401 A1.

In an embodiment, the process according to the present invention furthercomprises the step of cooling the first crude solder metal compositionand/or the second crude solder metal composition and/or the pre-refinedsolder metal composition down to a temperature of at most 825° C. toproduce a bath containing a first supernatant dross which by gravitybecomes floating upon a first liquid molten tuned solder phase. Theapplicants have found that this further downstream process step is ableto remove a significant amount of copper and other undesirable metalsfrom the crude solder. Further details for this step may be found in WO2018/060202 A1. The applicants have further found that this coolingstep, in combination with some of the further downstream process stepsperformed on this lead/tin stream, may offer an alternative, at leastpartially, to the pre-retreatment with silicon metal mentioned elsewherein this document. This is advantageous because silicon metal is a ratherscarce process chemical and it is of benefit if its use may be reducedand/or eliminated.

In an embodiment, the process according to the present invention furthercomprises the step of adding an alkali metal and/or an earth alkalimetal, or a chemical compound comprising an alkali metal and/or an earthalkali metal, to the first crude solder metal composition and/or to thesecond crude solder metal composition and/or to the pre-refined soldermetal composition and/or to the first liquid molten tuned solder phaseto form a bath containing a second supernatant dross which by gravitycomes floating on top of a second liquid molten tuned solder phase.

In an embodiment, the process according to the present invention furthercomprises the step of removing the second supernatant dross from thesecond liquid molten tuned solder phase, thereby forming a second tunedsolder.

In an embodiment, the process according to the present invention furthercomprises the step of removing the first supernatant dross from thefirst liquid molten tuned solder phase, thereby forming a first tunedsolder.

In an embodiment, the process according to the present invention furthercomprises the step of distilling the first tuned solder and/or thesecond tuned solder, wherein lead (Pb) is removed from the solder byevaporation and a distillation overhead product and a distillationbottom product are obtained, preferably by a vacuum distillation.

In an embodiment of the process according to the present inventionincluding the step of distilling at least one of the solder streams toremove lead (Pb) from the solder by evaporation and a distillationoverhead product and a distillation bottom product are obtained, thedistillation bottom product comprises at least 0.6% wt of lead. Thebenefits thereof are explained in WO 2018/060202 A1.

In an embodiment of the present invention, at least a part of theprocess is electronically monitored and/or controlled, preferably by acomputer program. The applicants have found that the control of stepsfrom the process according to the present invention electronically,preferably by a computer program, brings the advantage of a much betterprocessing, with results that are much more predictable and which arecloser to the process targets. For instance on the basis of temperaturemeasurements, if desired also pressure and/or level measurements and/orin combination with the results of chemical analyses of samples takenfrom process streams and/or analytical results obtained on-line, thecontrol program may control the equipment relating to the supply orremoval of electrical energy, supply of heat or of a cooling medium, aflow and/or a pressure control. The applicants have found that suchmonitoring or control is particularly advantageous with steps that areoperated in continuous mode, but that it may also be advantageous withsteps that are operated in batch or semi-batch. In addition andpreferably, the monitoring results obtained during or after theperformance of steps in the process according to the present inventionare also of use for the monitoring and/or control of other steps as partof the process according to the present invention, and/or of processesthat are applied upstream or downstream of the process according to thepresent invention, as part of an overall process within which theprocess according to the present invention is only a part. Preferablythe entire overall process is electronically monitored, more preferablyby at least one computer program. Preferably the overall process iselectronically controlled as much as possible.

The applicants prefer that the computer control also provides that dataand instructions are passed on from one computer or computer program toat least one other computer or computer program or module of the samecomputer program, for the monitoring and/or control of other processes,including but not limited to the processes described in this document.

The applicants prefer to operate particular steps of the processaccording to the present invention in a top blown rotary converter(TBRC), optionally a furnace as disclosed in U.S. Pat. No. 3,682,623,FIGS. 3-5 and their associated description, or a furnace commonly knownas a Kaldo furnace or Kaldo converter. The applicants particularlyprefer to use this type of furnace in the steps in which a chemicalreaction is taking place and/or in which an equilibrium is desiredbetween a molten slag phase and an underlying molten metal phase.

The applicants have found that this type of furnaces allows to processcomplex materials, materials which generate a high amount of slag phase,and material with large variations in terms of physical appearance aswell as in chemical composition. This type of furnace is able to acceptas feeds slags from other process steps and/or large pieces of solidmaterials, i.e. feedstocks that are much more difficult to introduceinto other types of furnace designs.

Such furnaces bring the advantage that the furnace may be rotated, suchthat a more intensive contact between solids and liquids, and betweendifferent liquid phases may be obtained, which allows to approach and/orreach the desired equilibrium between the phases faster.

Preferably the rotation speed of the furnace is variable, such that therotation speed of the furnace may be adapted to the process step whichis performed in the furnace. Process steps requiring reaction and movingthe furnace content towards equilibrium prefer a high rotation speed,while other process steps, such as when solid fresh feed needs to bemelted, may prefer a low rotation speed or possibly even no rotation atall.

Preferably the inclination angle of the furnace is variable, whichallows for a better control of the mixing, and therewith also of thereaction kinetics. A variable inclination angle also allows for a betterstart-up on solid feeds, preferably at a low inclination angle, untilsufficient and sufficiently hot liquid, and hence more fluid liquid, hasbeen formed to keep the remaining solids afloat.

The applicants prefer under particular conditions to operate the furnaceat least periodically not in the conventional rotating mode but in aso-called “rocking mode”, i.e. alternately rotating the furnace inopposite directions only a part of a full 360° rotation. The applicantshave found that this mode of operation may avoid possibly extreme forceson the furnace driving equipment when the furnace would be fullyrotating with the same content. The applicants prefer to apply this modeof operation when there is still a relatively high amount of solids inthe furnace charge and too low a liquid presence for keeping thesesolids afloat, or when the liquid in the furnace is still poorly fluid,e.g. because it is still rather cold.

The applicants prefer the TBRC to have a refractory lining, and morepreferably that lining having two layers. Preferably the inner layer ofthe lining, i.e. the layer in contact with the furnace content, is madeof a material that visually brightens up at the high temperatures of thefurnace content during full operation, while the underlying layermaterial remains dark when it is exposed to the vessel internaltemperatures. This setup allows a rapid spotting of defects in thelining by simple visual inspection during furnace operation.

The outer layer of the lining thus acts as a kind of safety layer. Theapplicants prefer that this safety lining has a lower thermalconductivity than the inner lining layer.

When installing the lining of the TBRC, the lining preferably beingconstructed by arranging individual and conically shaped refractorybricks, the applicants prefer to provide a sacrificial layer in betweenindividual lining elements or bricks, such as a layer of cardboard orroofing. This brings the advantage, as the furnace temperature heats upduring its first campaign, that the sacrificial layer incinerates anddisappears, and makes room for the thermal expansion of the bricks.

Several steps in the process according to the present invention preferthat the underlying molten metal phase is tapped from the furnace whilethe supernatant liquid slag phase is still in the furnace. Theapplicants prefer to tap this liquid metal by means of a drain or taphole in the furnace refractory lining. The applicants prefer to plugthis hole by means of a sacrificial metal rod during the furnacemovements of the operation. In order to prepare the metal tapping, theapplicants prefer to burn out this rod while it is kept above thefurnace liquid level, and to temporarily plug the burned out tap holewith a combustible plug, e.g. made of cardboard, after which the furnaceis turned into the metal tapping position. The applicants have foundthat the time of incinerating the combustible plug provides the time toturn the furnace into the metal tapping position and the tap hole topass the slag phase.

For heating the furnace with external heat supply, the applicants preferto use a burner which is burning a mixture of fuel and oxygen source,rather than introducing the fuel and the oxygen source separately intothe furnace. The applicants have found that such a mixing burner may bemore difficult to operate, but that it brings the advantage that theflame may be more accurately be directed to the preferred spot insidethe furnace.

The applicants have found that the ratio of fuel relative to the oxygensource may readily be used to control the oxidative/reductive furnaceregime inside the furnace, and hence assist in adjusting and/orcontrolling the direction of the chemical reactions that are supposed totake place inside the furnace.

The applicants have found that those steps as part of the processaccording to the present invention in which cold feedstocks areintroduced may generate dioxins and/or volatile organic compounds (VOC).The applicants prefer to perform these process steps in furnaces thatare equipped with proper equipment to capture dioxins and/or VOC's fromthe exhaust vapours. The applicants have found that the process may beoperated in a way that only a part of the furnaces need such exhausttreatment equipment, while for the other furnaces dust collection and/orfiltering is sufficient for meeting the legally imposed emissionstandards. The process according to the present invention includesseveral occasions for transferring a liquid molten metal and/or slagphase from one furnace to another. The applicants have found that thistransfer is most conveniently performed using transfer ladles. In orderto protect the construction materials of the transfer ladles, theapplicants prefer to provide the ladles with an internal layer of solidslag coating.

Example

The following example shows a preferred embodiment of the presentinvention. The example is further illustrated by the FIG. 1, which isshowing a flow diagram of the core part of the process according to thepresent invention. In this process part are recovered, from a variety ofvarious feedstocks and starting from a black copper composition 1, arefined anode grade copper product 9, a high copper metal compositionby-product 22, two crude solder metal composition products 18 and 26,and three spent slags 12, 20 and 28.

In the FIG. 1, the numbers represent the following claim features:

-   1. Black copper composition feedstock to step b) (100)-   2. Fresh feed to step b) (100)-   3. First copper refining slag-   4. First enriched copper metal phase-   5. Fresh feed to step h) (200)-   6. Second copper refining slag-   7. Second enriched copper metal phase-   8. Third copper refining slag-   9. Third enriched copper metal phase—Anode Grade-   10. Second lead-tin based metal composition-   11. Second dilute copper metal composition-   12. First spent slag-   13. First lead-tin based metal composition-   14. Sixth solder refining slag to the first liquid bath (450) before    step d) (500)-   15. First dilute copper metal composition-   16. First solder refining slag-   17. First Pb and/or Sn containing fresh feed to step e) (600)-   18. First crude solder metal composition-   19. Second solder refining slag-   20. Second spent slag-   21. Fourth lead-tin based metal composition-   22. First high-copper metal composition—portion removed from the    process-   23. Third solder refining slag-   24. Fourth solder refining slag-   25. Second Pb and/or Sn containing fresh feed to step n) (1000)-   26. Second crude solder metal composition-   27. Fifth solder refining slag-   28. Third spent slag-   29. Third lead-tin based metal composition-   30. First high-copper metal composition—portion recycled to step b)    and/or step d)-   31. Fresh feed to step j) (300)-   50. First copper containing fresh feed to step f) (700)-   51. Fresh feed to step p) (1200)-   52. Fresh feed to the second liquid bath (550) before step l) (800)-   53. Sixth solder refining slag recycled to step e) (600)-   55. Second copper containing fresh feed to step o) (1100)-   56. Fresh feed to step c) (400)-   57. Fresh feed to the first liquid bath (450) before step d) (500)-   58. Fresh feed to step m) (900)-   450 First liquid bath-   550 Second liquid bath-   100 Process step b)-   200 Process step h)-   300 Process step j)-   400 Process step c)-   500 Process step d)-   600 Process step e)-   700 Process step f)-   701 Process step g)-   800 Process step l)-   801 Recycle of stream 30 from step l) to process step b) and/or d)-   900 Process step m)-   901 Process step s), i.e. the recycle of stream 11 from step m) to    process step c)-   1000 Process step n)-   1100 Process step o)-   1200 Process step p)-   1201 Process step q)—Recycle of part of the sixth solder refining    slag (14) from step p) to the first liquid bath (450) and/or (53) to    process step e) (600)-   1202 Process step r)—Recycle of the fourth lead-tin based metal    composition (21) from step p) to the second liquid bath (550).

Step b) (100): A top blown rotary converter (TBRC), herein used as arefining furnace for step b) (100), was charged with 21,345 kg of blackcopper 1 from an upstream melting furnace, 30,524 kg of a firsthigh-copper metal composition 30 recycled from the downstream processstep l) (800) as part of a previous process cycle, and 86,060 kg offresh feed 2. The fresh feed 2 mainly consisted of bronze, red brass andsome feedstocks rich in copper but low in other valuable metals. Thecompositions and amounts of all the feeds to the furnace charge of stepb) (100) are shown in Table I. To the feeds thus charged was added anamount of silica flux in the form of sand flux sufficient to obtain thedesired effects of phase separation and/or slag fluidity. The feed wasmelted and/or heated under oxidizing conditions and partially withblowing of oxygen while the furnace was rotated.

TABLE I Step b) (100) Black Copper First High-Cu metal Fresh Feed 1 30 2Mt/charge 21.345 30.524 86.060 Mton % wt Mton % wt Mton % wt Cu 16.15375.68% 28.143 92.20% 68.410 79.49% Sn 1.114 5.22% 0.522 1.71% 1.3801.60% Pb 2.218 10.39% 0.531 1.74% 3.116 3.62% Zn 0.989 4.63% 0.005 0.02%2.470 2.87% Fe 0.336 1.57% 0.002 0.01% 1.747 2.03% Ni 0.428 2.00% 1.1053.62% 0.868 1.01% Sb 0.043 0.20% 0.171 0.56% 0.085 0.10% Bi 0.005 0.03%0.012 0.04% 0.013 0.02% As 0.013 0.06% 0.017 0.06% 0.014 0.02%

A significant amount of the zinc present in the feed was fumed out ofthe furnace. At the end of the first oxidation step b) (100), the firstcopper refining slag 3 was poured off and transferred to a slagretreatment furnace for being subjected to process step c) (400). Thisfirst copper refining slag 3 was rich in lead, tin, zinc and iron. Thedetailed composition of this slag 3 as well as the first enriched coppermetal phase 4 and dust produced during step b) (100), together withtheir amounts, are shown in Table II. The first enriched copper metalphase 4 was transferred to another TBRC for being subjected to processstep h) (200).

TABLE II Step b) (100) First Cu First enriched Refining copper metalSlag - 3 phase - 4 Dust Mt/charge 27.061 116.371 1.47 Mton % wt Mton %wt Mton % wt Cu 3.231 11.94% 111.367 95.70% 0.221 15.00% Sn 1.810 6.69%1.059 0.91% 0.147 10.00% Pb 3.875 14.32% 1.760 1.51% 0.221 15.00% Zn3.023 11.17% 0.000 0.00% 0.441 30.00% Fe 2.076 7.67% 0.005 0.00% 0.0000.00% Ni 1.012 3.74% 1.396 1.20% 0.000 0.00% Sb 0.052 0.19% 0.249 0.21%0.000 0.00% Bi 0.001 0.00% 0.031 0.03% 0.000 0.00% As 0.006 0.02% 0.0380.03% 0.000 0.00%

Step h) (200): To the first enriched copper metal phase 4, 27,091 kg ofcopper rich fresh feed 5 was added, and also an amount of sand fluxsufficient to obtain the desired effects of phase separation and/or slagfluidity. This fresh feed 5 consisted of some extra black copper fromthe upstream smelter in addition to copper rich solid material forcooling the furnace temperature. The composition and amounts of thefeeds to the furnace charge of step h) (200) are set forth in Table III.

TABLE III Step h) (200) First enriched copper metal Fresh Feed phase - 45 Mt/charge 116.371 27.091 Mton % wt Mton % wt Cu 111.367 95.70% 23.79492.48% Sn 1.059 0.91% 0.277 1.08% Pb 1.760 1.51% 0.579 2.25% Zn 0.0000.00% 0.513 1.99% Fe 0.005 0.00% 0.209 0.81% Ni 1.396 1.20% 0.131 0.51%Sb 0.249 0.21% 0.015 0.06% Bi 0.031 0.03% 0.004 0.01% As 0.038 0.03%0.002 0.01%

Oxidation of the furnace content was performed by blowing oxygen intothe furnace content. At the end of the second oxidation step, the secondcopper refining slag 6 was poured off and transferred to another slagretreatment furnace for being subjected to step d) (500). The remainingsecond enriched copper metal phase 7 was transferred to another TBRC forbeing subjected to step j) (300). The composition and amounts of thesecond copper refining slag 6 and the second enriched copper metal phase7 are shown in Table IV. As may be seen in Table IV, the metal phase 7had significantly been enriched in copper content, in comparison withthe furnace feed streams 4 and 5 in Table III.

TABLE IV Step h) (200) Second Cu Second enriched Refining copper metalSlag 6 phase - 7 Mt/charge 17.230 128.573 Mton % wt Mton % wt Cu 7.16141.56% 126.573 98.45% Sn 1.237 7.18% 0.083 0.06% Pb 2.004 11.63% 0.3160.25% Zn 0.515 2.99% 0.000 0.00% Fe 0.214 1.24% 0.000 0.00% Ni 0.6393.71% 0.874 0.68% Sb 0.109 0.63% 0.154 0.12% Bi 0.009 0.05% 0.026 0.02%As 0.007 0.04% 0.033 0.03%

Step j) (300): To the second enriched copper metal phase 7, another22,096 kg of copper rich fresh feed 31 was added. The composition andamounts of the feeds to the furnace charge of step j) (300) are shown inTable V.

TABLE V Step j) (300) Second enriched copper metal Fresh Feed phase - 731 Mt/charge 128.573 22.096 Mton % wt Mton % wt Cu 126.573 98.45% 20.64793.44% Sn 0.083 0.06% 0.077 0.35% Pb 0.316 0.25% 0.177 0.80% Zn 0.0000.00% 0.192 0.87% Fe 0.000 0.00% 0.109 0.49% Ni 0.874 0.68% 0.029 0.13%Sb 0.154 0.12% 0.003 0.02% Bi 0.026 0.02% 0.001 0.00% As 0.033 0.03%0.000 0.00%

Oxygen blowing was performed on the furnace content, and at the end ofthe blowing period an amount of sand flux was added sufficient to obtainthe desired effects of phase separation and/or slag fluidity, beforepouring off the third copper refining slag 8. The remaining anode gradecopper metal phase 9 was removed from the furnace for furtherprocessing, e.g. purification by electrorefining. The composition andamounts of the third copper refining slag 8 and of the anode gradecopper 9 are given in Table VI. As can be seen in Table VI, the metalphase 9 had been further enriched in copper content, as compared withthe furnace feed streams 7 and/or 31 in Table V.

TABLE VI Step j) (300) Third enriched Third Cu copper metal Refiningphase - 9 - Slag 8 Anode Grade Mt/charge 17.024 134.781 Mton % wt Mton %wt Cu 12.535 73.63% 133.546 99.08% Sn 0.138 0.81% 0.022 0.02% Pb 0.4652.73% 0.025 0.02% Zn 0.192 1.13% 0.000 0.00% Fe 0.109 0.64% 0.000 0.00%Ni 0.375 2.20% 0.542 0.40% Sb 0.099 0.58% 0.057 0.04% Bi 0.006 0.04%0.020 0.02% As 0.006 0.03% 0.028 0.02%

Step c) (400): 26,710 kg of the first copper refining slag 3 (with thecomposition given in Table VII), was introduced into another TBRC usedas slag retreatment furnace, together with 6,099 kg of fresh feed 56 and11,229 kg of a second dilute copper metal phase 11 obtained from aprocess step m) (900) from a previous process cycle and together with23,000 kg of a second lead-tin based metal phase or composition 10obtained from a process step f) (700) from a previous process cycle. Tothis furnace content, 10,127 kg of scrap iron as reducing agent wasadded. Further added was an amount of sand flux sufficient to obtain thedesired effects of safety, phase separation and/or slag fluidity. Oncefilling was completed the furnace was rotated at a speed in the range of18-20 rpm. The composition and amounts of the feeds to the furnacecharge of step c) (400) are shown in Table VII.

TABLE VII Step c) (400) First Cu Second dilute Second Pb—Sn RefiningFresh Feed Cu metal based metal Slag - 3 56 phase - 11 phase - 10Mt/chge 26.710 6.099 11.229 23.000 Mton % wt Mton % wt Mton % wt Mton %wt Cu 3.189 11.94% 0.987 16.18% 6.960 61.98% 16.665 72.50% Sn 1.7876.69% 0.325 5.32% 2.095 18.66% 1.685 7.33% Pb 3.825 14.32% 0.419 6.87%0.775 6.90% 2.521 10.97% Zn 2.983 11.17% 0.178 2.92% 0.006 0.05% 0.3811.66% Fe 2.049 7.67% 1.440 23.61% 0.020 0.18% 1.233 5.36% Ni 0.999 3.74%0.135 2.21% 1.291 11.50% 0.429 1.87% Sb 0.052 0.19% 0.017 0.28% 0.0730.65% 0.044 0.19% Bi 0.001 0.00% 0.000 0.00% 0.002 0.02% 0.006 0.02% As0.006 0.02% 0.000 0.00% 0.003 0.03% 0.011 0.05%

When the reduction of copper, tin and lead had sufficiently beenprogressed, a first lead-tin based metal composition 13, dust and afirst spent slag 12 had been produced. The compositions and amounts ofthese products are given in Table VIII. The first spent slag 12 waspoured off and removed from the process. The first lead-tin based metalcomposition 13 was transferred to another TBRC to become part of thefirst liquid bath 450.

TABLE VIII Step c) (400) First Pb—Sn First spent based metal slag 12phase - 13 Dust Mt/chge 31.287 46.718 1.346 Mton % wt Mton % wt Mton %wt Cu 0.111 0.35% 28.105 60.32% 0.031 2.27% Sn 0.074 0.24% 5.645 12.11%0.170 12.64% Pb 0.156 0.50% 7.176 15.40% 0.276 20.52% Zn 2.372 7.58%0.568 1.22% 0.612 45.50% Fe 12.049 38.51% 2.047 4.39% 0.010 0.71% Ni0.012 0.04% 2.834 6.08% 0.002 0.12% Sb 0.000 0.00% 0.184 0.39% 0.0020.18% Bi 0.000 0.00% 0.008 0.02% 0.000 0.00% As 0.000 0.00% 0.016 0.03%0.004 0.31%

Step d) (500): For forming the first liquid bath 450, to the 46,718 kgof first lead-tin based metal composition 13 were added 17,164 kg of thesecond copper refining slag 6 (having the composition given in Table IV)together with 9,541 kg of fresh feed 57, and 474 kg of sixth solderrefining slag 14 (recycled from the downstream process step p) (1200) aspart of a previous process cycle). Further added was an amount of sandflux sufficient to obtain the desired effects of phase separation and/orslag fluidity. The compositions and amounts of the components of thefirst liquid bath 450, which formed the furnace charge for step d)(500), are shown in Table IX.

TABLE IX Step d) (500) First Pb—Sn Sixth Solder Second Cu based metalFresh Feed Refining Refining phase - 13 57 Slag - 14 Slag - 6 Mt/chge46.718 9.541 0.474 17.164 Mton % wt Mton % wt Mton % wt Mton % wt Cu28.105 60.32% 1.749 22.09% 0.015 3.08% 7.133 41.56% Sn 5.645 12.11%0.484 6.11% 0.021 4.51% 1.232 7.18% Pb 7.176 15.40% 0.677 8.54% 0.06012.69% 1.996 11.63% Zn 0.568 1.22% 0.308 3.89% 0.025 5.30% 0.513 2.99%Fe 2.047 4.39% 2.675 33.77% 0.134 28.21% 0.213 1.24% Ni 2.834 6.08%0.209 2.63% 0.002 0.33% 0.637 3.71% Sb 0.184 0.39% 0.028 0.35% 0.0000.01% 0.108 0.63% Bi 0.008 0.02% 0.000 0.00% 0.000 0.00% 0.009 0.05% As0.016 0.03% 0.000 0.00% 0.000 0.00% 0.007 0.04%

The mixture of slags and metal phase was reacted until in the slag phasethe concentrations of copper and/or nickel were sufficiently reduced.The reaction was forcing more tin and lead into the slag phase. At thatpoint the furnace was bottom-tapped thereby removing a first dilutecopper metal composition 15 from the furnace. The first solder refiningslag 16 together with approximately 1 metric ton left over from thefirst dilute copper metal phase 15 were passed to another TBRC for beingsubjected to the next step e) (600). The compositions and amounts ofboth product streams obtained from step 500, except for the 1 metric tonof metal phase that had remained with the slag phase, are set forth inTable X.

TABLE X Step d) (500) First Solder First dilute Refining Cu metal Slag -16 phase - 15 Mt/chge 28.200 49.792 Mton % wt Mton % wt Cu 1.047 3.71%35.387 71.07% Sn 1.375 4.87% 5.925 11.90% Pb 5.268 18.68% 4.541 9.12% Zn1.393 4.94% 0.023 0.05% Fe 5.059 17.94% 0.013 0.03% Ni 0.282 1.00% 3.3316.69% Sb 0.010 0.04% 0.304 0.61% Bi 0.000 0.00% 0.017 0.03% As 0.0000.00% 0.022 0.05%

The first dilute Cu metal phase 15 from step d) contained about 0.08% wtof silver (Ag) and 0.03% wt of sulphur.

Step e) (600): 14,987 kg of first lead and tin containing fresh feed 17was added to the first solder refining slag 16 before this mixture wasbeing reduced in step e) (600). The reduction was done by adding 8,017kg of scrap iron as reducing agent. Further added to the furnace as partof step e) (600) were 8,650 kg of the sixth solder refining slag 53,obtained from the downstream process step p) (1200) as part of aprevious process cycle, in addition to an amount of sand flux sufficientto obtain the desired effects of phase separation and/or slag fluidity.The compositions and amounts of the feeds forming the furnace charge forstep e) (600) are shown in Table Xl.

TABLE XI Step e) (600) First Solder 1st Pb + Sn Sixth Solder Firstdilute Refining containing Refining Cu metal Slag - 16 Fresh Feed - 17Slag - 53 phase - 15 Mt/chge 28.200 14.987 8.650 1.000 Mton % wt Mton %wt Mton % wt Mton % wt Cu 1.047 3.71% 1.361 9.08% 0.266 3.08% 0.71171.07% Sn 1.375 4.87% 4.184 27.92% 0.390 4.51% 0.119 11.90% Pb 5.26818.68% 7.738 51.63% 1.098 12.69% 0.091 9.12% Zn 1.393 4.94% 0.043 0.29%0.458 5.30% 0.000 0.05% Fe 5.059 17.94% 0.106 0.71% 2.440 28.21% 0.0000.03% Ni 0.282 1.00% 0.011 0.07% 0.029 0.33% 0.067 6.69% Sb 0.010 0.04%0.298 1.99% 0.001 0.01% 0.006 0.61% Bi 0.000 0.00% 0.002 0.01% 0.0000.00% 0.000 0.03% As 0.000 0.00% 0.000 0.00% 0.000 0.00% 0.000 0.05%

A substantial quantity of zinc was fumed out of the furnace contentduring this partial reduction step. The reduction was stopped when theSn concentration in the slag phase had attained about target level. Atthat point the furnace was again bottom-tapped to remove the first crudesolder metal composition 18 from the process. The first crude soldermetal composition 18 was further processed into lead and tin primeproducts. The second solder refining slag 19 was passed to another TBRCfor further treatment as part of step f) (700). The compositions andamounts of the first crude solder metal 18, the second solder refiningslag 19 as well as the dust obtained from step e) (600) are shown inTable XII.

TABLE XII Step e) (600) First Crude Second Solder Solder Metal RefiningComposition - 18 Slag - 19 Dust Mt/chge 23.132 36.667 1.551 Mton % wtMton % wt Mton % wt Cu 3.256 13.53% 0.116 0.39% 0.016 1.06% Sn 5.38922.40% 0.778 2.60% 0.150 9.64% Pb 13.224 54.97% 0.652 2.18% 0.318 20.52%Zn 0.087 0.36% 1.106 3.70% 0.706 45.50% Fe 0.282 1.17% 15.003 50.20%0.011 0.71% Ni 0.354 1.47% 0.032 0.11% 0.002 0.12% Sb 0.311 1.29% 0.0020.01% 0.003 0.18% Bi 0.002 0.01% 0.000 0.00% 0.000 0.00% As 0.000 0.00%0.000 0.00% 0.000 0.03%

Step f) (700): A further reduction step was performed on the secondsolder refining slag 19 by adding 1,207 kg of scrap iron as reducingagent. Further added as part of step f) (700) were 22,234 kg of firstcopper containing fresh feed 50 and an amount of sand flux sufficient toobtain the desired effects of safety, phase separation and/or slagfluidity. This fresh feed 50 consisted of some extra black copper fromthe upstream smelter in addition to some slag materials collectedleftover from other process steps. The compositions and amounts of thefeeds to the furnace charge of step f) (700) are given in Table XIII.

TABLE XIII Step f) (700) Second Solder Copper Refining Containing Slag -19 Fresh Feed - 50 Mt/chge 36.667 22.234 Mton % wt Mton % wt Cu 0.1160.39% 16.630 75.95% Sn 0.778 2.60% 1.003 4.58% Pb 0.652 2.18% 2.0529.37% Zn 1.106 3.70% 1.010 4.61% Fe 15.003 50.20% 0.509 2.32% Ni 0.0320.11% 0.405 1.85% Sb 0.002 0.01% 0.042 0.19% Bi 0.000 0.00% 0.005 0.03%As 0.000 0.00% 0.011 0.05%

When Cu, Sn and Pb in the slag were reduced down to at most 0.50% each,a second lead-tin based metal phase 10 and a second spent slag 20 hadbeen produced. The compositions and amounts thereof are given in TabledXIV. The second spent slag 20 was poured off and was removed from theprocess. The second lead-tin based metal composition 10 was passedonwards for the step c) (400) of the next process cycle before reducingthe first copper refining slag (3).

TABLE XIV Step f) (700) Second Pb-Sn based metal Second spent phase - 10slag 20 Mt/chge 23.000 37.523 Mton % wt Mton % wt Cu 16.665 72.50% 0.1150.31% Sn 1.685 7.33% 0.090 0.24% Pb 2.521 10.97% 0.188 0.50% Zn 0.3811.66% 1.726 4.60% Fe 1.233 5.36% 15.384 41.00% Ni 0.429 1.87% 0.0100.03% Sb 0.044 0.19% 0.000 0.00% Bi 0.006 0.02% 0.000 0.00% As 0.0110.05% 0.000 0.00%

Step l) (800): 17,024 kg of the third copper refining slag 8 (having thecomposition shown in Table VI) was fed to a TBRC used as slagretreatment furnace together with 14,920 kg of copper rich fresh feed 52and 49,792 kg of the first dilute copper metal phase 15 obtained fromstep d) (500). Further added was an amount of sand flux sufficient toobtain the desired effects of phase separation and/or slag fluidity.These materials were melted along with the fourth lead-tin based metalphase 21 (20,665 kg) obtained from the downstream process step p) (1200)as part of a previous process cycle. These feeds together composed thesecond liquid bath 550. Once the filling and melting was completed, thefurnace was rotated at a speed of 20 rpm. The compositions and amountsof the feeds to the slag retreatment furnace charge for step l) (800)are shown in Table XV.

TABLE XV Step l) (800) Fourth Pb—Sn First dilute Third Cu based metalFresh Feed Cu metal Refining phase - 21 52 phase - 15 Slag - 8 Mt/chge20.665 14.920 49.792 17.024 Mton % wt Mton % wt Mton % wt Mton % wt Cu16.483 79.76% 3.985 30.10% 35.387 71.07% 12.535 73.63% Sn 1.882 9.11%0.610 4.61% 5.925 11.90% 0.138 0.81% Pb 1.643 7.95% 3.104 23.45% 4.5419.12% 0.465 2.73% Zn 0.019 0.09% 0.792 5.98% 0.023 0.05% 0.192 1.13% Fe0.012 0.06% 1.363 10.29% 0.013 0.03% 0.109 0.64% Ni 0.533 2.58% 0.3162.39% 3.331 6.69% 0.375 2.20% Sb 0.063 0.31% 0.043 0.33% 0.304 0.61%0.099 0.58% Bi 0.006 0.03% 0.000 0.00% 0.017 0.03% 0.006 0.04% As 0.0110.05% 0.000 0.00% 0.022 0.05% 0.006 0.03%

The mixture was reacted, if needed in addition partially oxidized usingoxygen blowing, until the concentrations of copper and nickel in theslag had about reached their target values. At that point the furnacewas bottom-tapped for removing 64,500 kg of the first high-copper metalcomposition (streams 22 and 30 together) from the third solder refiningslag 23. The third solder refining slag 23, together with approximately6 metric tons of the first high copper metal phase that was kept withthe slag, was passed onto another TBRC for further treatment as part ofstep m) (900). The compositions and amounts of the product streams atthe end of step l) (800) are set forth in Table XVI, and this timeinclude the 6 metric tons of metal phase that remained with the slagphase on its way to the next treatment step.

TABLE XVI Step l) (800) First High Third Solder Cu metal Refining phase22 + 30 Slag 23 Mt/chge 70.500 39.276 Mton % wt Mton % wt Cu 59.46992.20% 3.182 8.10% Sn 1.103 1.71% 7.317 18.63% Pb 1.122 1.74% 8.51521.68% Zn 0.011 0.02% 1.013 2.58% Fe 0.004 0.01% 1.496 3.81% Ni 2.3353.62% 1.980 5.04% Sb 0.362 0.56% 0.114 0.29% Bi 0.026 0.04% 0.000 0.00%As 0.036 0.06% 0.000 0.00%

Of the first high copper metal composition in the furnace, 30,524 kgwere fed into the copper refining furnace as stream 30 for beginning anew step b) (100) of a next cycle. A further 33,976 kg were removed fromthe process as stream 22, for further processing.

Step m) (900): After removal of the (30,524 kg+33,976 kg=) 64,500 kg ofthe first high copper metal phase (22+30) from the furnace, the furnacecontent was passed onto another TBRC for further treatment as part ofstep m) (900). The mixture of the 39,276 kg of third solder refiningslag 23 and the 6 tons of metal having the composition of the first highcopper metal composition was partially reduced as part of step m) (900).Scrap iron was introduced as reducing agent. Further added to step m)were an amount of sand flux sufficient to obtain the desired effects ofphase separation and/or slag fluidity, and a minor amount (37 kg) offresh feed 58. The compositions and amounts of the feeds forming thefurnace charge for step m) (900) are given in Table XVII.

TABLE XVII Step m) (900) Third Solder Metal phase having Refining FreshFeed remained with the Slag - 23 58 slag (23) Mt/chge 39.276 0.037 6.0000 Mton % wt Mton % wt Mton % wt Cu 3.182 8.10% 0.001 2.38% 5.532 92.20%Sn 7.317 18.63% 0.001 3.31% 0.103 1.71% Pb 8.515 21.68% 0.004 10.88%0.104 1.74% Zn 1.013 2.58% 0.002 5.94% 0.001 0.02% Fe 1.496 3.81% 0.01027.53% 0.000 0.01% Ni 1.980 5.04% 0.000 0.22% 0.217 3.62% Sb 0.114 0.29%0.000 0.00% 0.034 0.56% Bi 0.000 0.00% 0.000 0.00% 0.002 0.04% As 0.0000.00% 0.000 0.00% 0.003 0.06%

The reduction step m) (900) was stopped when the concentrations ofcopper and nickel in the slag phase had sufficiently been reduced. Atthat point, the furnace was bottom-tapped to remove an amount of 11,229kg of second dilute copper metal composition 11 for further treatment instep c) (400) of a next process cycle. A fourth solder refining slag 24together with about 1,400 kg of metal having the composition of thesecond dilute copper metal phase 11 was passed onto another TBRC forbeing subjected to step n) (1000). The compositions and total amounts ofthe second dilute copper metal phase or composition 11 and of the fourthsolder refining slag 24 are shown in Table XVIII, whereby the 1,400 kgof metal phase which is remaining with the slag phase is included in thetotal amount reported for the second dilute copper metal phase 11.

TABLE XVIII Step m) (900) Second dilute Fourth Solder Cu metal Refiningphase - 11 Slag - 24 Mt/chge 12.629 41.342 Mton % wt Mton % wt Cu 6.96061.98% 1.389 3.36% Sn 2.095 18.66% 5.069 12.26% Pb 0.775 6.90% 7.74318.73% Zn 0.006 0.05% 1.009 2.44% Fe 0.020 0.18% 9.037 21.86% Ni 1.29111.50% 0.752 1.82% Sb 0.073 0.65% 0.066 0.16% Bi 0.002 0.02% 0.000 0.00%As 0.003 0.03% 0.000 0.00%

The second dilute Cu metal phase 11 from step m) contained about 0.11%wt of silver (Ag) and 0.01% wt of sulphur.

Step n) (1000): After the 11,229 kg of second dilute copper metal phase11 was tapped from the furnace, the remaining furnace content wastransferred to another TBRC for performing step n) (1000). 11,789 kg ofsecond lead and tin containing fresh feed 25 was added as part of stepn) (1000) and the furnace content was further reduced. The reduction wasdone by adding 9,692 kg of scrap iron as reducing agent, along with anamount of sand flux sufficient to obtain the desired effects of phaseseparation and/or slag fluidity. The compositions and amounts of thedifferent furnace feeds for step n) (1000) are shown in Table XIX.

TABLE XIX Step n) (1000) Fourth Solder Fresh Second dilute Refining FeedCu metal Slag - 24 25 phase - 11 Mt/chge 41.342 11.789 1.400 Mton % wtMton % wt Mton % wt Cu 1.389 3.36% 0.728 6.18% 0.868 61.98% Sn 5.06912.26% 1.864 15.81% 0.261 18.66% Pb 7.743 18.73% 8.790 74.56% 0.0976.90% Zn 1.009 2.44% 0.019 0.16% 0.001 0.05% Fe 9.037 21.86% 0.070 0.59%0.003 0.18% Ni 0.752 1.82% 0.003 0.02% 0.161 11.50% Sb 0.066 0.16% 0.0740.63% 0.009 0.65% Bi 0.000 0.00% 0.037 0.32% 0.000 0.02% As 0.000 0.00%0.000 0.00% 0.000 0.03%

The partial reduction step was stopped when the concentration of tin inthe slag phase had attained about target level. At that point thefurnace was again bottom-tapped to remove the second crude solder metalcomposition 26 from the furnace, leaving only the fifth solder refiningslag 27 in the furnace. The second crude solder metal composition 26 wasfurther processed into lead and tin prime products. The fifth solderrefining slag 27 was passed onto another TBRC for performing step o)(1100). The compositions and amounts of the second crude solder metal 26and of the fifth solder refining slag 27 are set forth in Table XX.

TABLE XX Step n) (1000) Fifth Solder Second Crude Refining Solder 26Slag 27 Mt/chge 23.080 41.956 Mton % wt Mton % wt Cu 2.934 10.57% 0.0540.13% Sn 6.245 22.49% 0.975 2.32% Pb 16.080 57.90% 0.550 1.31% Zn 0.0000.00% 1.032 2.46% Fe 1.363 4.91% 17.373 41.41% Ni 0.895 3.22% 0.0210.05% Sb 0.149 0.54% 0.000 0.00% Bi 0.038 0.14% 0.000 0.00% As 0.0000.00% 0.000 0.00%

Step o) (1100): A further reduction step was performed on the fifthsolder refining slag 27 by adding to it 922 kg of scrap iron as reducingagent along with 23,735 kg of copper containing fresh feed 55 and anamount of sand flux sufficient to obtain the desired effects of safety,phase separation and/or slag fluidity. The second copper containingfresh feed 55 consisted primarily of extra black copper from theupstream smelter. The compositions and amounts of the feeds to step o)(1100) are given in Table XXI.

TABLE XXI Step o) (1100) Fifth Solder Copper Refining Containing Slag 27Fresh Feed - 55 Mt/chge 41.956 23.735 Mton % wt Mton % wt Cu 0.054 0.13%15.456 67.27% Sn 0.975 2.32% 0.997 4.34% Pb 0.550 1.31% 2.022 8.80% Zn1.032 2.46% 1.097 4.77% Fe 17.373 41.41% 1.603 6.98% Ni 0.021 0.05%0.391 1.70% Sb 0.000 0.00% 0.040 0.17% Bi 0.000 0.00% 0.005 0.02% As0.000 0.00% 0.011 0.05%

The reduction was continued until an acceptable spent slag quality wasobtained. When this target was reached, a third lead-tin based metalphase 29 and a third spent slag 28 had been produced, the compositionsand amounts of which are given in Table XXII. The third spent slag 28was poured off and was removed from the process. The third lead-tinbased metal composition 29 was transferred to the TBRC which wasintended for performing step p) (1200).

TABLE XXII Step o) (1100) Third Pb—Sn based metal Third spent phase - 29slag 28 Mt/chge 22.300 45.542 Mton % wt Mton % wt Cu 15.446 69.56% 0.1550.34% Sn 1.923 8.66% 0.069 0.15% Pb 2.417 10.88% 0.205 0.45% Zn 0.3471.56% 1.812 3.98% Fe 1.598 7.20% 18.522 40.67% Ni 0.406 1.83% 0.0150.03% Sb 0.041 0.18% 0.000 0.00% Bi 0.005 0.02% 0.000 0.00% As 0.0110.05% 0.000 0.00%

Step p) (1200): To the third lead-tin based metal composition 29 wereadded 5,204 kg of fresh feed 51 along with an amount of sand fluxsufficient to obtain the desired effects of phase separation and/or slagfluidity. Subsequently, by partial oxidation, most of the iron and zincwere oxidized from the metal phase into the slag phase. The compositionsand amounts of the products from this oxidation step p) (1200) are shownin Table XXIII.

TABLE XXIII Step p) (1200) Third Pb—Sn based metal Fresh Feed phase - 2951 Mt/chge 22.300 5.204 Mton % wt Mton % wt Cu 15.446 69.56% 1.40232.04% Sn 1.923 8.66% 0.368 8.42% Pb 2.417 10.88% 0.386 8.83% Zn 0.3471.56% 0.156 3.56% Fe 1.598 7.20% 0.989 22.61% Ni 0.406 1.83% 0.158 3.61%Sb 0.041 0.18% 0.023 0.54% Bi 0.005 0.02% 0.000 0.01% As 0.011 0.05%0.000 0.00%

When the oxidation of iron and zinc had sufficiently been progressed, afourth lead-tin based metal composition 21 and a sixth solder refiningslag 14 had been produced, the compositions and amounts of which aregiven in Table XXIV. The sixth solder refining slag 14 was poured offand was added at least partially as stream 14 to the first liquid bath(450) and/or at least partially as stream 53 to the step e) (600) of thenext process cycle. The fourth lead-tin based metal composition 21 wastransferred to another TBRC to become part of the second liquid bath 550and for performing the step l) (800) as part of the next process cycle.

TABLE XXIV Step p) (1200) Fourth Pb—Sn Sixth Solder based metal Refiningphase - 21 Slag 14 Mt/chge 20.665 9.124 Mton % wt Mton % wt Cu 16.48379.76% 0.281 3.08% Sn 1.882 9.11% 0.411 4.51% Pb 1.643 7.95% 1.15812.69% Zn 0.019 0.09% 0.483 5.30% Fe 0.012 0.06% 2.573 28.21% Ni 0.5332.58% 0.030 0.33% Sb 0.063 0.31% 0.001 0.01% Bi 0.006 0.03% 0.000 0.00%As 0.011 0.05% 0.000 0.00%

The process steps 100-1200 involving molten metal and/or slag phases areall operated at a temperature in the range of 1100 to 1250° C. Dependingon the purpose of the step, its operating temperature may preferably beclose to the upper or to the lower end of this temperature range.

The applicants have found that the embodiment of the process asdescribed in this Example may be performed in a limited number ofTBRC's. The applicants have been able to perform this process in as fewas 8 furnaces, several of them preferably being of the TBRC type. Theapplicants prefer to perform this process in as few as 6 furnaces, morepreferably in only 5 furnaces, even more preferably in only 4 furnaces,yet more preferably in only 3 furnaces.

Having now fully described this invention, it will be appreciated bythose skilled in the art that the invention can be performed within awide range of parameters within what is claimed, without departing fromthe scope of the invention, as defined by the claims.

1. A process for producing a crude solder composition, comprising theprovision of a first solder refining slag which slag comprises at least12% wt together of tin and lead and at most 10.0% wt together of copperand nickel, the process further comprising the steps of: e) partiallyreducing the first solder refining slag, thereby forming a first crudesolder metal composition and a second solder refining slag, followed byseparating the second solder refining slag from the first crude soldermetal composition; and f) partially reducing the second solder refiningslag, thereby forming a second lead-tin based metal composition and asecond spent slag followed by separating the second spent slag from thesecond lead-tin based metal composition, wherein a copper containingfresh feed is added to step f).
 2. The process according to claim 1wherein the copper containing fresh feed comprises at least one of blackcopper, spent copper anode material and reject copper anode material.3-30. (canceled)
 31. The process according to claim 1, furthercomprising the following step: d) producing the first solder refiningslag by partially oxidizing a first liquid bath comprising copper and atleast one solder metal, thereby forming a first dilute copper metalcomposition and the first solder refining slag, followed by separatingthe first solder refining slag from the first dilute copper metalcomposition.
 32. The process according to claim 31, further comprisingthe step of: c) partially reducing a first copper refining slag therebyforming a first lead-tin based metal composition and a first spent slag,followed by separating the first spent slag from the first lead-tinbased metal composition, the first lead-tin based metal compositionforming the basis for the first liquid bath. 33-40. (canceled)
 41. Theprocess according to claim 32, further comprising the steps of: a)providing a black copper composition comprising a significant amount ofcopper together with a significant amount of tin and/or lead; b)partially oxidizing the black copper composition, thereby forming afirst enriched copper metal phase and the first copper refining slag,followed by separating the first copper refining slag from the firstenriched copper metal phase; and feeding the first copper refining slagto step c). 42-45. (canceled)
 46. The process according to claim 41,further comprising the step of: h) partially oxidizing the firstenriched copper metal phase, thereby forming a second enriched coppermetal phase and a second copper refining slag, followed by separatingthe second copper refining slag from the second enriched copper metalphase.
 47. The process according to claim 46, further comprising thefollowing step: i) at least one of adding at least a part of the secondcopper refining slag to the first liquid bath and adding at least a partof the second copper refining slag to step d).
 48. The process accordingto claim 46, further comprising the following steps: j) partiallyoxidizing the second enriched copper metal phase, thereby forming athird enriched copper metal phase and a third copper refining slag,followed by separating the third copper refining slag from the thirdenriched copper metal phase; k) at least one of adding at least a partof the third copper refining slag to the first dilute copper metalcomposition from step d), thereby forming a second liquid bath and/oradding at least a part of the third copper refining slag to step l); andl) partially oxidizing the second liquid bath, thereby forming a firsthigh-copper metal composition and a third solder refining slag, followedby separating the third solder refining slag from the first high-coppermetal composition.
 49. The process according to claim 48, furthercomprising the following step: m) partially reducing the third solderrefining slag, thereby forming a second dilute copper metal compositionand a fourth solder refining slag, followed by separating the fourthsolder refining slag from the second dilute copper metal composition.50. The process according to claim 49, further comprising the followingstep: n) partially reducing the fourth solder refining slag, therebyforming a second crude solder metal composition and a fifth solderrefining slag, followed by separating the second crude solder metalcomposition from the fifth solder refining slag.
 51. The processaccording to claim 50, further comprising the following step: o)partially reducing the fifth solder refining slag, thereby forming athird lead-tin based metal composition and a third spent slag, followedby separating the third spent slag from the third lead-tin based metalcomposition. 52-66. (canceled)
 67. The process claim 1, in which a blackcopper is added to at least one of steps b), f) and o), wherein theblack copper is produced by a smelter step.
 68. The process according toclaim 1, wherein at least one of the first crude solder metalcomposition and the second crude solder metal composition is pre-refinedusing silicon metal to produce a pre-refined solder metal composition.69. The process according to claim 1, further comprising the step ofcooling at least one material selected from the first crude solder metalcomposition, the second crude solder metal composition and thepre-refined solder metal composition down to a temperature of at most825° C. to produce a bath containing a first supernatant dross which bygravity becomes floating upon a first liquid molten tuned solder phase.70. The process according to claim 1, further comprising the step ofadding at least one compound selected from an alkali metal, an earthalkali metal, and chemical compounds comprising at least one of analkali metal and an earth alkali metal, to at least one materialselected from the first crude solder metal composition, the second crudesolder metal composition, the pre-refined solder metal composition, andthe first liquid molten tuned solder phase to form a bath containing asecond supernatant dross which by gravity comes floating on top of asecond liquid molten tuned solder phase.
 71. The process according toclaim 70, further comprising the step of removing the second supernatantdross from the second liquid molten tuned solder phase, thereby forminga second tuned solder.
 72. The process according to claim 69, furthercomprising the step of removing the first supernatant dross from thefirst liquid molten tuned solder phase, thereby forming a first tunedsolder.
 73. The process according to claim 71, further comprising thestep of distilling at least one material selected from the first tunedsolder and the second tuned solder, wherein lead (Pb) is removed fromthe solder by evaporation and a distillation overhead product and adistillation bottom product are obtained, preferably by a vacuumdistillation. 74-75. (canceled)
 76. The process according to claim 72,further comprising the step of distilling at least one material selectedfrom the first tuned solder and the second tuned solder, wherein lead(Pb) is removed from the solder by evaporation and a distillationoverhead product and a distillation bottom product are obtained,preferably by a vacuum distillation.